The hair incident happened to a work friend of mine at a cafeteria like restaurant in downtown Newark, NJ. She removed the hair in her sandwich, but I forget if she ate it all or just part if it. I would have brought it up and gotten a new one.
My worst experience at a restaurant, was getting sick after having a fish meal, at home.
Best, was being given a new meal when salmon I had ordered in a Columbus restaurant was undercooked. Not only was a new meal given, they gave me a slice of tall chocolate cake to take home. That was at Cap City Diner. This is a really nice dining place, despite the name, not really a typical diner type place.
The only true wisdom is in knowing you know nothing.