I was reading an article in the paper about a cook who got 6 months in jail because he put hairs in a customer's steak. He didn't say what kind of hairs... ugh. I also read that the customer had been rude, which is a big no-no.
I have seen this in restaurants before (people deliberately making an effort to be contentious and snotty) and I will never understand why they insist on demeaning the people who serve them food. It's not too smart.
I also try to never send food back. Especially not French Toast.