# eBay hacking: Can a shill bidder discover a legit bidder's max bid amount? **URL:** \ **Category:** Factual Questions\ **Created:** [December 6, 2004, 10:22pm UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428 "2004-12-06T22:22:29Z")\ **Posts on this page:** 11\ **Page:** 4
**Author:** ![agatto2](https://avatars.discourse-cdn.com/v4/letter/a/bbce88/32.png) [@agatto2](https://boards.straightdope.com/u/agatto2)\ **Post date:** [February 1, 2012, 10:08pm UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/61 "2012-02-01T22:08:16Z")
> [@md2000](#): > > The point is, if someone is autobidding or sniping to win, they will bid _ **above** _ a round number. The thinking goes - they probably bid $800, I would bid 810, but they probably thought of that and autobid 815, so I’ll go with 817. > > Bidding just \*\*\*under \*\*\*the round number suggests you want lose, i.e. shill. > > So maybe someone had figured out a system. Is this still the case, or are these all zombie anecdotes? Did eBay actually fix anything? I find that hard to believe. Heres the pictures that i took of my screen…Notice how the schill bidder bids two times on everything he bids on… and they are all duplicates. Just Saying - Ebay is the one who has the most to gain on this. Most rep guys I dont think would give up thier accounts to bing $20 [http://img819.imageshack.us/img819/9490/ebayscamshot2.th.png](http://imageshack.us/photo/my-images/819/ebayscamshot2.png/) [http://img20.imageshack.us/img20/5454/ebayscamshot1.th.png](http://imageshack.us/photo/my-images/20/ebayscamshot1.png/) ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [February 1, 2012, 11:41pm UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/62 "2012-02-01T23:41:00Z")
> [@md2000](#): > > The point is, if someone is autobidding or sniping to win, they will bid _ **above** _ a round number. No, they \*might \*if they are smart enough. And some won’t be smart enough. Think about all ebay sales and how they would look assuming there \*isn’t \*some systematic scam going on: - there are I assume hundreds of thousands if not millions of sales on ebay every day. - a significant proportion of those will involve sniping: my experience is well over 50%. - a significant proportion of snipes will be at slightly less than the eventual sale value because what people choose as a max bid is not at all random. For many items people are going to have a fair idea of market value and arrive at similar conclusions about what their max bid should be. So there is a good chance that the winner will only bid slightly above a sniper - some of those snipes are going to be by people who aren’t canny enough to use an odd number and just whack in a round number. Your own reasoning on why you put in some odd number ($817) is based on the assumption that other people probably put in round numbers ($800), so you must accept there are people who do so. So out of all this what you would expect to see, assuming there is no systematic shill bidding with inside knowledge? What you would expect to see is hundreds of instances every day of people’s winning bid being pushed up to just below their max by other last minute round number bids. There is, as expected, anecdotal evidence this occurs. Yawn. To have any evidence of systematic shill bidding with inside knowledge you would have to have evidence of people’s winning bid being pushed up to just below their max by other last minute round number bids _occurring at a rate greater than would be predicted by chance_. And there is no evidence of that. > [@agatto2](#): > > Heres the pictures that i took of my screen…Notice how the schill bidder bids two times on everything he bids on… and they are all duplicates. So what? He probably just places bids with two different free sniping services so that if one goes down he still gets his bid in. How is this evidence of anything nefarious. ---
**Author:** ![The\_Second\_Stone](https://avatars.discourse-cdn.com/v4/letter/t/bbe5ce/32.png) [@The\_Second\_Stone](https://boards.straightdope.com/u/The_Second_Stone)\ **Post date:** [February 2, 2012, 12:27am UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/63 "2012-02-02T00:27:56Z")
> [@jasonh300](#): > > I did this once when an opposing bidder pissed me off by outbidding me on a bunch of different car parts auctions. > > The high bid was showing $50.00. As it turned out the high bidder had put in a proxy of $75.00. From $25.00 to $99.00, the bids are done in increments of $1.00. > > I put in a bid of $60.00, which was the maximum amount I wanted to pay and the other guy’s proxy bid kicked in making the high bid $61.00. I decided to try and make the other guy pay the maximum amount. I put in a bid for $61.48 (or some other odd ‘cents’ amount like that). The max bid went up to $62.48. I went in 50 cent incremements until I put in $73.48. The maximum bid went to $74.48. When I put in $74.98, the maximum bid went to $75.00 even. Because the max bid only went to $75.00, I knew I’d hit his proxy bid because the max bid didn’t go up to $75.98. > > This didn’t benefit me in any way except for getting the satisfaction of making the guy pay $75.00 for something he could’ve had for $61.00. After I did that, there were no more bidding wars from that guy. 🙂 Does this still work? I’ve felt that this has been done to me in the past. When I see an ebay item that I want, I carefully determine the true maximum I would want to pay and then mark it on my calendar and during the last minute will start setting up my bid and only click it in during the last 15 seconds. I’ve almost always won the auction at a fair price this way, sometimes at quite a bargain. I never bid stuff up early. ---
**Author:** ![insectlover](https://avatars.discourse-cdn.com/v4/letter/i/a5b964/32.png) [@insectlover](https://boards.straightdope.com/u/insectlover)\ **Post date:** [December 29, 2013, 5:08pm UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/64 "2013-12-29T17:08:04Z")
On eBay there is no monitoring on eBay’s part for another bidder to be using the same computer/IP address as the eBay lister who is selling the item. It tends to be the seller/lister who pushes up the bid last minute to get the maximum price - sometimes ahead of time as well. It is just a coincidence here that they got very close to your max bid. I suggest you see if this is possible to do when you list an item then you can see for yourself that what I am saying is true. eBay does not monitor this as they also want the buyer to pay the highest price possible as that is how they make their profits- Yes, eBay is a white collar mafia and they make their rules as they go along - they are out for profit and power along with Paypal. They have in place now where you are unable to identify bidder but look at the bidder and if they have near 100% bid activity with the seller who you are bidding an item on from I can assure you it is the seller pushing up the bid using another account. ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [December 29, 2013, 6:41pm UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/65 "2013-12-29T18:41:50Z")
> [@insectlover](#): > > On eBay there is no monitoring on eBay’s part for another bidder to be using the same computer/IP address as the eBay lister who is selling the item. Wrong. We got flagged and booted for a month for doing this. And, I was tryong to actually by the item personally. Not boosting the bid. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [December 29, 2013, 6:47pm UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/66 "2013-12-29T18:47:59Z")
> [@samclem](#): > > Wrong. We got flagged and booted for a month for doing this. And, I was tryong to actually by the item personally. Not boosting the bid. You were trying to buy an item that you had listed? What’s the point? Ego trip? ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [December 29, 2013, 11:18pm UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/67 "2013-12-29T23:18:31Z")
> [@samclem](#): > > Wrong. We got flagged and booted for a month for doing this. And, I was tryong to actually by the item personally. Not boosting the bid. Bwuh? ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [December 30, 2013, 3:20am UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/68 "2013-12-30T03:20:35Z")
At a guess, **samclem** was listing an item (a coin?) for a customer/client - and was also (legitimately) interested in trying to buy it. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [December 30, 2013, 4:27am UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/69 "2013-12-30T04:27:38Z")
**Walrus** is right, and people are making it more complicated than it is. First, let me say that I wish people could simply bid their max and come back later to see if they won. We often can’t, thanks to psychology. Of all the nontrivial auctions I’ve been in, I never won when I posted my limit early, only when I posted it shortly before the auction ends. As a result, I find I have to “snipe” if that’s what you call it. I’m just avoiding making the item seem attractive because I’m willing to bid on it. But Walrus’s point is different, and valid, and I found myself doing that too, for the same reason. For items that aren’t unusual, there are often several auctions going on at the same time. I want to win only one auction, so I can’t bid on them all. I could just bid on the first one to end, but a new auction might appear with a similar but better item, and I can’t retract my original bid. Or something completely different might appear, and I might decide I’d rather spend my limited funds on that. So, while I hate having to wait for an auction to nearly end before bidding, that’s what I usually do. I don’t get caught up in the frenzy. I generally know what I’m willing to pay well beforehand, and don’t change my mind in the heat of the moment. ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [December 30, 2013, 4:31am UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/70 "2013-12-30T04:31:07Z")
> [@Xema](#): > > At a guess, **samclem** was listing an item (a coin?) for a customer/client - and was also (legitimately) interested in trying to buy it. That was the case. ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [December 30, 2013, 4:33am UTC](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428/71 "2013-12-30T04:33:37Z")
> [@samclem](#): > > Wrong. We got flagged and booted for a month for doing this. And, I was tryong to actually by the item personally. Not boosting the bid. > [@Musicat](#): > > You were trying to buy an item that you had listed? What’s the point? Ego trip? The company, for which I work, listed the item. I had to bid on it to buy it. [Previous page](https://boards.straightdope.com/t/ebay-hacking-can-a-shill-bidder-discover-a-legit-bidders-max-bid-amount/278428.md?page=3)