I worked in fast food for 11 years, from entry-level to restaurant manager.
I never saw any tampering or heard any credible reports of it.
My only experience of food service was a high-school job at Chic-fil-A in the '80s. Having worked there for close to a year, I would happily eat a meal off any of the food prep surfaces in the kitchen - they were, and I assume still are, meticulous about cleaning the restaurant. Never heard anyone even joke about messing with someone’s food.
Worked in fast food, catering, mom & pop local place, and gigantic university dorm kitchen. Never saw it; never heard a credible report.
Worked in about 16 restaurants over 20 years.
Never did I see anyone do anything to food with the intent to make it unwholesome or inedible.
OTOH, I’ve seen people unintentionally do many, many, many things that makes the food unwholesome or inedible, but that was due to carelessness or lack of training, not intent. (I very rarely eat out anymore, and when I do, it is because I personally know the owners of the restaurant.)
Now, when I worked at a mexican restaurant, we did find it amusing lighting people up that would say things like “Give it to me as hot as you got it”, or “You can’t make it spicy enough for me”. Nothing unwholesome about a few drops of Pure Cap. 
I saw this on the Google news page this morning, and I simply had to click the link, even though it was Fox news. Warning, there is a video on this page but it does not auto play. I didn’t click it, but judging from the headline I would assume that it’s NSFW.
Headline:
Tennessee man accused of dipping testicles in customer’s salsa
Ah, the ol’ Huevos Diablo, eh?
No bueno.
So, that wasn’t guacamole?
I worked at a Chinese restaurant in high school and this was absolutely not the case. The chef/owner was a stingy old Chinese guy, they didn’t practice the best sanitation, but even he would not have done that. Not even to use for the fried rice. Could you find an outlier, prolly; general practice no way.
He certainly did suddenly not understand English and vigorously used a giant cleaver to whack at veggies when the health inspector came by. But that was all Kabuki theater and the health inspector was in on the act.
Well, I worked as a bus-boy all through my mid to late teens, so I never directly saw the food being prepared, but I never heard any stories of tampering either. These were upscale restaurants though, so I doubt they’d hire anyone with an unsavory reputation. Being fired for something like that is a career killer.
Here’s one jerk who got off lightly.
I suspect it’s honored more in the breach than in the observance. I also suspect it’s a handy rumor to have circulating to keep customers in check, regardless if it never actually happens.
In the film Princess Caraboo, the butler Mr. Phrixos serves the princess soup, and as she’s lifting her spoon to her mouth, whispers in her ear, “I pissed in your soup.” He was only testing to see if she was lying about not understanding English. (Spoiler alert: She was English.) She played it cool and swallowed it right down. She was in it for the long con.
It was several lifetimes ago, but I spent about a year working at a fast food place and several more in movie concessions, both as an employee and a manager. While I saw my share of jerk customers, I never saw anybody tamper with food in retaliation. If I had ever caught anybody working for me doing so, I would have fired them on the spot.
So to avoid the situation I don’t eat where police eat. It seems cops may get unrequested DNA samples. Around here it seems cops only eat where they can see the food prepared or at buffets (also helps give them weight to throw around) ie Wendy’s, Subway or all you can eat pizza.
Interesting. It’s been my experience that when in an unfamiliar town that eating where police eat is usually a good reasonably priced restaurant. Of course I have no way of knowing whether or not I got any “special” seasoning.
Most fast food restaurants have the food prep area in full view of the counter, or at least they do here. Even if you used the drive-up, a customer might observe this tampering and alert the manager.
I worked in restaurants from age 14 until I graduated from college when I was 30, and never heard of any deliberate adulteration. Oh, there was the story about someone at the semi-upscale place where I worked in college preparing a burger for Gerald Ford and putting a pubic hair in it, but the guy who told me was kind of a weirdo and wouldn’t tell me, ahem, “whose” it was. :dubious:
4.5 years at a pizza place, saw it happen twice.
both times it was on takeout orders placed in person by people being high order assholes right out the starting gate.
Closest I’ve seen was the arsehole chef who would deliberately try and get tiny bits of meat in meals ordered by vegetarians- using the cooked meat knife and chopping board. He was only there for 2 weeks before being fired though, due to being a bit of a psycho.
My cousin told me about one he saw a few times, when he worked at McDonalds as a teen (this would have been mid 90s, before many of the regs were tightened up, when most of the staff were teenagers). They’d have a few items off the breakfast menu pre-cooked and either wrapped or ready to assemble, but then at 11, when the menu stopped, any remaining would be chucked out.
A couple of times at something like 11.15, a customer would come in and demand something off the breakfast menu, refusing to take ‘no’ for an answer, because obviously there were more ingredients and the cooks were just being lazy refusing to make one fresh.
The cooks had already cleaned up the grills and were prepping for the lunch menu, and they weren’t setting up the whole breakfast section again for one item for one demanding git, so they’d pick the (sometimes wrapped, sometimes not) thrown out items from the trash, wipe any dirt off, re-heat them a bit, and serve.
I’m inclined to believe him that it happened back then, but friends who’ve worked there since say no way would that happen now. Everyone’s watched too closely.
I remember some years ago Waffle House being sued because some black patrons were served grits with dead flies in them. I don’t recall the outcome of the suit, but I seem to recall paraphrasing their defense as “Hey, we’re Waffle House; a lot of our food has flies in it.”
I never worked at McDonald’s, but I have worked at Burger King and Arby’s, and I can believe this story.
:smack: I just remembered the ‘Cole Slaw’ incident. But it wasn’t in a restaurant.