My mom was a waitress for maybe 30 years. At one point I asked her about the customers she had to wait on in all these years. I asked her who were her meanest customers. She said they were vegans.

Most of the vegan customers who she served would get really demanding and would start going all "I'm a vegan, I can't eat this" and would lecture her on the food when ordering. They used to send food back too.
I'm guessing this is shocking to nobody. All those years she used to work as a waitress and it's funny how they stood out the most. Just shows you how insufferable most of them are, really. If you think about it.