1. Bad breath - cigarette breath is the worst, but bad breath in general really kills the moment for me.
2. The attitude change - when they promise the world in the bar, but once you get them back to your room, they change attitude and just race to get it over and get your cash asap!
3. Similar to #2 - clock watchers.
For the record, I actually don't mind armpit hair - hate seeing it in pictures of a girl (kinda ruins her attractiveness!) but in real life doing the deed its okay.