Last place I worked at that actually banned customers was at a pizza place in a college town that did a lot of late night deliveries back when restaurants delivered their own food.

Bounced checks, being rude to employees, not being there when the delivery driver arrived were the biggest ones. After hitting a critical mass on fraternities we started banning the whole fraternity if we ran into issues and they sorted that out fast by getting their members to behave better and other people would volunteer to buy the pizza if the person fell asleep or couldn’t be found. Pretty much everyone who screwed up was given another chance by paying off their balance and the bounced check fee or apologizing to staff.

There was also one guy who never tipped and kept calling and saying is pizza was wrong so the owner made his pizza one night and delivered it himself, then banned the guy when he called and lied about the delivery. He was banned for life along with the people who were racist/sexist. The owner was a jerk when it came to his ridiculous capitalist expectations, but he did defend his employees from external assholes.

It was the rare occasion of someone being so stupid that they accidentally started their own cell phone scam.

This guy could not decide on what phone he wanted. He had two plans with all of his relatives on them. Whenever someone became eligible for a contract renewal, he would buy himself a phone and give his old one to one of those relatives. He also was very picky, and would try to return his phones for dumb reasons like “I haven’t turned my phone off since I got it, and now it’s running slow.”

He would hop between different stores and customer service to get warranty replacements for his older phones, and exchanges for new ones, and because he was passing phones between accounts, a phone that he had for a year, would look like it was just bought a few days ago, so he would be offered a brand new one, or the option to try another model. When he came into my store complaining, something didn’t seem right, so I spent an entire day researching where all his phones came from and where they went. I discovered that for years, he was costing us thousands of dollars burning through brand new phones and requesting credits for his inconvenience.

The last time we told him that we couldn’t help him, he said he’d never come back, we thanked him.

One of my previous customers was a mentally ill and delusional elderly lady. She called me about a non-existent plumbing problem in her house, supposedly caused by her neighbor, who she claimed breaks in and messes with her stuff. According to her, everything wrong inside or outside her house was because of her neighbor’s sabotage. She even mentioned plans to kill him. Not exactly the kind of person you want to turn your back on, but also someone who would have been extremely easy to take advantage of. I basically talked her out of redoing the entire plumbing in her bathroom, and we finally settled on me re-aligning her kitchen cabinet doors that - yes, you guessed it - her neighbor had ‘messed with.’

It was quite sad, really. She asked me twice whether I thought her stories sounded crazy, so she was clearly somewhat aware of her condition. I just didn’t know how to deal with someone like that. I refuse to lie, but I also don’t want to tell her she’s losing it. I don’t mind senile people, but I didn’t feel safe around her.

Hundreds of gigabytes of horse porn, right in a folder on his desktop called “horse”. The thumbnail of the folder made it incredibly clear what the folder was and what was in it, which was made extra clear by the max zoom his desktop icons were set to. (it was like, no joke, almost 1/10th the screen).

Fun fact: that was the day I learned my state doesn’t have mandatory reporting laws for animal abuse, only csam.

He touched a waitress in a way she didn’t want to be touched.

He was creepin’ on other customers. When he was asked to tone it down, especially when it came to talking to minors, he got mad and started yelling and shoving chairs.

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He made threats at gunpoint.

When I worked in customer service, a guy kept calling in and waiting until he got a woman so he could say vulgar shit. Another guy called me a “n*gger bitch” and he was put on letters only. I know he couldn’t tell what race I was over the phone, but I immediately said “fuck you” and hung up and then proceeded to panic about losing my job once the initial shock wore off. I didn’t lose my job though. 👍🏾

At the video rental store, the customer that returned a DVD case reeking of cigarettes and full of cockroaches. I had seen the customer before and always read the notes about the latest gross ass thing they’d done that flashed up on screen when serving them because all the other staff hated them and would write these complaints. Despite that I didn’t really remember them particularly or have much of a run in with them.

I happened to be the one on shift when they were to discover they’d been banned though. They tried to pick up some movies to rent and I had to explain that I couldn’t rent to them because they were banned. They asked why and I told them that it says here you returned a DVD case full of cockroaches and they responded indignantly “What!? Is that IT!?” They definitely weren’t denying it and seemed very surprised this was a bannable offence.

Woman was clearly mentally ill, extremely belligerent, seeking tech support. At some point, store manager was saying something about trying to accommodate her and she said, “You don’t get points for trying.” Store manager turned around and said, “Call security.”

Phone support later called us to arrange help and I explained that she wasn’t welcome and would have to go to a different store. Fortunately, there are many where I live and she didn’t have to travel very far if she accepted that answer (dunno the outcome).

I worked at a headshop in the late 80’s amd early 90’s.

We sold nitrous oxide for whipped cream (and to inhale). It’s a very short lived high…mebbe a couple of minutes for the average person. It came in 24 packs of nitrous cylinders for about $50 US.

There was a guy who would come in when we opened at 10 AM and buy a case (144 cylinders) for personal use, and be back in the store before 6 PM to buy another case. Eventually over a few weeks he was buying multiple cases every time. His lips started cracking and bleeding from the cold, and then turning blue. We found out he was going to our other stores in the area and finally banned him.

We had people buy crack pipes and other smoking paraphernalia too, but that one haunted me. I had never seen someone fall that hard into addiction, or that fast. He was obviously miserable and could not stop.

A recurring customer having habit of delaying to pay the bar tab because he’s “too drunk”. Usually took him weeks and multiple asking before he paid his bar tab in full.

This time he bought a bunch of pretty girls lots of expensive drinks, at the end of the night he is so drunk that nobody can reason with him to pay (but we suspect he’s faking it as always). So we put his bill in his tab and let him go.

The next day he act like he doesn’t remember anything and refused to acknowledge that he was buying anyone else drinks even with the CCTV footage of him on that night (and of course refused to pay his tab).

This went on for 2 weeks before the head bartender get into a fight with him. The customer ended up with a black eye and got banned from the bar. He doesn’t press any charges.

I couldn’t remember his bill total in the end, but it was close to 2k.

I work as an IT consultant so I don’t have to deal with any of the crap people in traditional customer roles do, but there have been a couple of customers we’ve agreed to mutual part ways with. Mostly due to them having unrealistic expectations.

One client expected us to basically be their 24/7 help desk, but only paid for like 20-30 hours a month. He wanted someone in their office from 8-5. He was like they can work on other stuff, but I need them to be here in case someone needs them. We were not an MSP. We didn’t do help desk. The original contract was to help with a date center migration with flex hours to support after the move. We did project work with mainly senior consultants. This was a company with 1 IT guy and maybe 100 employees. As soon as the contract came up for renewal we were done.

I’ve a few fun stories.

I spent some years around the turn of the century running a video arcade in a shopping mall. (Kids, ask your parents what both of those were.) Kids regularly got themselves kicked out for violence, whether toward the machines (sometimes hard enough to chip paintwork) or against each other (always fun when a round of Street Fighter results in a round of Regular Fighter.) I once banned a kid who had stolen a roll of prize tickets behind my back while I was reloading a machine’s ticket supply, and very intelligently tried to come back the next day to buy prizes with the still-intact unused roll. I once got a family banned from the entire mall because they decided to leave a scared toddler - maybe five years old, no ability to play the games or money to spend on them, and no discernible ability to communicate in English - alone in the arcade - a dark, crowded, and noisy place with its own open door leading directly to the parking lot - while they went off to do their shopping in the rest of the mall. The kid was turned over to mall security who got the cops involved.

More recently I worked for some years in a 3D-print-to-order factory which I’ll call “Shapeways,” for that was its name. Custom tabletop RPG dice sets were popular items; considerably more expensive than getting a standard set from the local hobby shop, but available in all sorts of bespoke designs in cool materials. One customer was apparently so dissatisfied with their dice order that they not only sent a bunch of Chaotic Evil emails and phone calls about it, but included direct threats to go down to the factory personally to teach us some sort of lesson. This resulted in their account being shut down, authorities getting involved, and the factory hiring an armed security guard for a few months over a set of dice which could simply have been reprinted or refunded. (Shapeways has since shut down, but as far as I know it was not over unsatisfactorily-printed dice.)