# Do advertisers not know I already bought the thing they're trying to sell me? **URL:** \ **Category:** In My Humble Opinion\ **Tags:** commercials-ads\ **Created:** [May 15, 2024, 1:54pm UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590 "2024-05-15T13:54:18Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [May 16, 2024, 3:16am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/21 "2024-05-16T03:16:26Z")
> [@Grrr](#): > > So I bought a couch yesterday online. > > So now all these advertisers have polluted my screens with couch advertisements. What are these “advertisements” of which you speak? I use uBlock Origin, and don’t see any of them. Why do you allow ads? ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [May 16, 2024, 3:32am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/22 "2024-05-16T03:32:01Z")
> [@kenobi\_65](#): > > Speaking as an ad guy: I agree; it’s dumb to give an ad to someone who’s literally just bought your product. But, that said…it’s not a matter of bad advertising; it’s a matter of having two different systems, run by two different companies, that aren’t set up to communicate with each other, and that use different data. > > The ad-buy system uses cookies or search history to target you with ads, and it’s undoubtedly run by a third party, like Google or Conversant, rather than by the company you bought from. They serve you ads for what you searched for, because they have no idea if you actually have bought it or not, or were just browsing. The sales site you bought your game from is run by the game company (or a third-party shopping cart vendor), and uses the personal information and account info you provide to them. Still. The company that is sending me the ads for this board game is the same company I searched for the game on and the same company I then bought it from. The advertising algorithm was able to make note of the fact I conducted the search; it should be able to make not of the fact I bought the game. The company presumably paid for this advertising algorithm on the basis that targeting ads for particular products to certain individuals was worth the cost. But in this case, they paid to have the ads specifically targeted at somebody who has zero interest in buying the product. They would have gotten better effect by just sending out random ads with no targeting. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [May 16, 2024, 3:42am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/23 "2024-05-16T03:42:26Z")
> [@Little\_Nemo](#): > > The company presumably paid for this advertising algorithm on the basis that targeting ads for particular products to certain individuals was worth the cost. But in this case, they paid to have the ads specifically targeted at somebody who has zero interest in buying the product. They would have gotten better effect by just sending out random ads with no targeting. Or, another way to look at it: they buy an ad service from Google, which targets ads to people who have done some sort of online search for particular games, knowing that many people search, but don’t always buy right away. Unfortunately, because it’s not easy (if even possible) to exclude those who actually _buy_ that particular game from them from the ad buy (because it’s two completely different computer systems, run by two different companies), they wind up advertising to a relatively small sliver who are no longer in the market. And, yes, thus annoying a few people. But, everyone else who sees those ads are, in fact, extremely well-targeted by those ads. ---
**Author:** ![China\_Guy](https://avatars.discourse-cdn.com/v4/letter/c/779978/32.png) [@China\_Guy](https://boards.straightdope.com/u/China_Guy)\ **Post date:** [May 16, 2024, 4:14am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/24 "2024-05-16T04:14:10Z")
This is a pet peeve of mine, and irks my drawers. I bought a 2 pack of hiking poles, yet somehow the algorithms think I need more? ---
**Author:** ![CaveMike](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cavemike/32/16379_2.png) [@CaveMike](https://boards.straightdope.com/u/CaveMike)\ **Post date:** [May 16, 2024, 4:15am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/25 "2024-05-16T04:15:54Z")
> [@kenobi\_65](#): > > Unfortunately, because it’s not easy (if even possible) to exclude those who actually _buy_ that particular game from them from the ad buy (because it’s two completely different computer systems, run by two different companies), Agreed. It would amount to each vendor having to tell their ad providers ‘customer X bought product Y’. It’s a lot more traffic, complexity, and shared personal data. The vendors are probably selling that data, not giving it away for free. > [@Little\_Nemo](#): > > I was looking for an out-of-print board game. I saw a game company had two copies. I bought one last week. If you feel like sharing, I’m curious about what game it was. A first printing of Candyland with a ladder mistakenly inverted? ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [May 16, 2024, 4:19am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/26 "2024-05-16T04:19:15Z")
> [@CaveMike](#): > > It would amount to each vendor having to tell their ad providers ‘customer X bought product Y’. And, the data that the vendor has on their customers is generally _not_ going to be compatible with the data that the ad provider has on them. The vendor knows you by your account information (email address, real name and address, etc.); the ad provider knows you by a profile they’ve built up on your browsing history, which generally does _not_ contain things like your email address or real name. They know (roughly) where you live – at least at a ZIP level – due to what they can learn from your ISP information, and what node you’re logged in through; they don’t generally have access to your actual real-world address. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [May 16, 2024, 4:20am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/27 "2024-05-16T04:20:09Z")
> [@China\_Guy](#): > > I bought a 2 pack of hiking poles, yet somehow the algorithms think I need more? Again, the algorithms know that you _searched_ for hiking poles. They do not know that you _bought_ them. Different programs, different companies. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [May 16, 2024, 4:22am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/28 "2024-05-16T04:22:19Z")
> [@CaveMike](#): > > If you feel like sharing, I’m curious about what game it was. A first printing of Candyland with a ladder mistakenly inverted? Dale of Merchants Collection ---
**Author:** ![CaveMike](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cavemike/32/16379_2.png) [@CaveMike](https://boards.straightdope.com/u/CaveMike)\ **Post date:** [May 16, 2024, 4:26am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/29 "2024-05-16T04:26:15Z")
I used to periodically search for something from one of my hobbies just to ‘set’ the ads. For example I’d do a quick search for a boutique guitar brand. Then for the next week while scrolling through the news, the ads would all be photos of cool guitars. > [@Little\_Nemo](#): > > Dale of Merchants Collection Looks very cool, thanks! ---
**Author:** ![zbuzz](https://avatars.discourse-cdn.com/v4/letter/z/e19b73/32.png) [@zbuzz](https://boards.straightdope.com/u/zbuzz)\ **Post date:** [May 16, 2024, 4:28am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/30 "2024-05-16T04:28:47Z")
The cause could also be because of a scenario such as you searched for the product on your phone, but then purchased it on your computer. If the ad platform doesn’t know it’s you on both devices (through matched unique identifiers or however they do it), you’re still going to see the ads on your phone at least due to the searching. ---
**Author:** ![zbuzz](https://avatars.discourse-cdn.com/v4/letter/z/e19b73/32.png) [@zbuzz](https://boards.straightdope.com/u/zbuzz)\ **Post date:** [May 16, 2024, 4:29am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/31 "2024-05-16T04:29:29Z")
> [@snowthx](#): > > Never mind buying something, just _mentioning_ something in the presence of your smartphone will generate spam for that thing. That really doesn’t happen. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [May 16, 2024, 4:29am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/32 "2024-05-16T04:29:56Z")
> [@zbuzz](#): > > If the ad platform doesn’t know it’s you on both devices (through matched unique identifiers or however they do it) I can tell you that, in most cases, yes, the ad platforms do know that it’s “you” across your different devices, unless you take steps to anonymize your online activity. ---
**Author:** ![nightshadea](https://avatars.discourse-cdn.com/v4/letter/n/7ba0ec/32.png) [@nightshadea](https://boards.straightdope.com/u/nightshadea)\ **Post date:** [May 16, 2024, 4:44am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/33 "2024-05-16T04:44:14Z")
facebook is the worst on that …if you look at one ad you will get spammed by everything that crawled out from a rock and is selling some version of what you looked at ---
**Author:** ![zbuzz](https://avatars.discourse-cdn.com/v4/letter/z/e19b73/32.png) [@zbuzz](https://boards.straightdope.com/u/zbuzz)\ **Post date:** [May 16, 2024, 7:44am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/34 "2024-05-16T07:44:33Z")
> [@kenobi\_65](#): > > I can tell you that, in most cases, yes, the ad platforms do know that it’s “you” across your different devices, unless you take steps to anonymize your online activity. I don’t doubt it’s a “most cases” scenario, but with a couple hundred million iOS devices being activated every year, I think there is a probably a pretty sizable segment of users who aren’t being tracked across devices (or at least are being tracked much less efficiently) because of Apple’s various default privacy settings that discourage tracking. Without digital fingerprinting or other less-than-legitimate methods, the tracking data from the iOS device isn’t going to be able to be linked to a user’s home Windows computer for the most part. The $10 billion drop in Facebook’s revenue from a few years ago not long after Apple turned off app tracking by default probably bears this out (they blamed it on Apple, anyway). From your job in advertising, how often do you come across companies using methods such as device fingerprinting to get around those kinds of restrictions? ---
**Author:** ![snowthx](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowthx/32/10660_2.png) [@snowthx](https://boards.straightdope.com/u/snowthx)\ **Post date:** [May 16, 2024, 11:15am UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/35 "2024-05-16T11:15:59Z")
> [@zbuzz](#): > > That really doesn’t happen. It really did: we were sitting around one evening before dinner and my wife said “I want a milkshake” and then we discussed where to get one. 10 minutes later her phone chimes for an arriving email. She checks and guess what - email offer from The Habit (burger chain) for a free milkshake with purchase of one of their meals. Yes, your phone can be listening to you, unless you take steps for it not to. And yes, we did go to The Habit that evening and used that coupon. ---
**Author:** ![zbuzz](https://avatars.discourse-cdn.com/v4/letter/z/e19b73/32.png) [@zbuzz](https://boards.straightdope.com/u/zbuzz)\ **Post date:** [May 16, 2024, 1:23pm UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/36 "2024-05-16T13:23:14Z")
If it really happened, it was really most likely just a coincidence. In just about any normal circumstance, so barring bugs, malware and the like, your phone isn’t serving up ads based on your conversations without you explicitly allowing it to do so. Unless you can explain why the thousands of other products your wife has mentioned in front of her phone never resulted in immediately receiving ads for those products. Not to mention the billions of times per day this doesn’t happen to anyone else. Or is Big Milkshake the only player in this space? ---
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [May 16, 2024, 1:33pm UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/37 "2024-05-16T13:33:16Z")
According to a documentary I watched. The algorithm is just that good. It doesn’t need to listen to your conversations. ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [May 16, 2024, 1:42pm UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/38 "2024-05-16T13:42:03Z")
I work at The Internet and have worked on the creation of several stores and @kenobi_65 is absolutely correct here with their analysis. ---
**Author:** ![snowthx](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowthx/32/10660_2.png) [@snowthx](https://boards.straightdope.com/u/snowthx)\ **Post date:** [May 16, 2024, 4:33pm UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/39 "2024-05-16T16:33:08Z")
I cannot explain why or how it happened, but there are reports of others experiencing the same sort of thing, so it’s not unknown. I acknowledge there does not seem to be any scientific studies proving this is a widespread happening. ---
**Author:** ![Jophiel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jophiel/32/66_2.png) [@Jophiel](https://boards.straightdope.com/u/Jophiel)\ **Post date:** [May 16, 2024, 5:02pm UTC](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590/40 "2024-05-16T17:02:27Z")
> [@snowthx](#): > > 10 minutes later her phone chimes for an arriving email. Well, if it was Big Shake listening, they’re not doing a great job of sending coupons. When I want a shake, ten minutes later I’m already consuming a shake and not waiting to see if I get coupons. [Previous page](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590.md?page=1) [Next page](https://boards.straightdope.com/t/do-advertisers-not-know-i-already-bought-the-thing-theyre-trying-to-sell-me/1001590.md?page=3)