I have worked in customer service in one way or another for over thirty years ... started as a busboy in my family's restaurant, and boy, have I met some obnoxious customers. I try very hard not to do the things that would brand be as difficult, but I have, when for example, buying the last dress, asked for a discount because a minor repair was necessary and I wanted the dress.
My all-time favorites:
Retail department store customer who demanded that I refund her cash for a credit card sale ... refused to take any reasonable explanation . Argued, ranted, screamed, yelled, demanded a manager (who are always so quick to respond to these people) I finally told her if I could figure out how to refund cash off a credit card sale I would be lounging on a private island somewhere ... on her dime. Manager walks in, bursts out laughing and walks back out. Chicken!
Gentleman consumes the ENTIRE seafood platter, mopping up the clarified butter with our fresh homemade bread, then claims it was bad. I don't think so! (Luckily, I was the ranking family member that night!
Customer who did not like that my boss, his salesperson, was not available to take his call and told me, "You need to be spanked."
Smart alec answers, "My daddy wasn't man enough to do it, and neither are you."
Sadly, I've never been fired for mouthing off at customers. When I worked at the department store, I was actually a "safe" employee who filled in at the customer service counter. The video surveillance there had audio. The security personnel would sit and listen to me and laugh their butts off while I fielded question after question!