When they don't appear to prepare them for any response other than "fine thanks"?
I was at a pub restaurant tonight and the girl who served us asked, whist scooting past, "are your meals ok?". I had a query and had to call her back as she was literally across the room before she had finished the sentence.
She had no idea what to say to me and was even a little defensive.
Why do places do this when they arent prepared for people to answer that the meal isn't great?