Lazy servers who would rather guess than go get an answer. I have some food allergies and I'll ask if an ingredient is in the soup and they say they don't think so. I ask if they can find out for sure and instantly they know it is not there. I will never order that item as I won't chance it. Smart servers say 'Let me find out' and go to the kitchen for verification.

The other pet peeve is low booths since I am short and would like to be able to see what is on the table.