re: Retailer/server employees: worst ever customer?

Ran a gym for years. I have some pretty awesome stories. One of the worst members we ever had was an insufferable old man who always complained about everything. He was on an insurance program and came to the gym for free. One day he starts beating on the TV on the treadmill because he sucked with technology. One of my employees goes over to help him and he starts berating her. I wasn't in the mood to deal with his crap and told him that he made all of my staff miserable and I kicked him out.
He came back in the gym the next day because he went home and his wife asked him why he was home from the gym so soon. When he told her that he got kicked out she told him that he probably deserved it because he "is an ornery old a-hole" and she made him come back to apologize.

It was always the members who paid the least that caused the most problems.