Let's see. It hasn't happened yet, but..........
People who smack their food (chew with their mouth open or talk with a mouth full of food).
People who blow their nose at the table. That is too gross ----- go to the bathroom or at least out into the hallway. No one wants to hear that while they are eating.
Sorry, but these are huge etiquette faux pas and I get nauseated seeing (or hearing) it.
It really is nasty and if it were consistant habits with a tablemate, I would likely skip all other formal dining and eat in the alternate places or ask for a change of seating.
I don't care for screaming kids either, or really LOUD people who cause scenes.
I guess I just like a quiet but fun formal dining experience. We can laugh and have a good time at a table without upsetting the rest of the other diners. And there is no excuse for being gross at the table.