I'm kind of bitchy and people generally know fast if I don't like them. When I get aggressive, I start using "sir" or "ma'am" to address people.
I generally don't like when guys make comments on looks like "this (general race) is hot" or "nice thighs, you work out?" It opens me up to making comments about beer guts, man boobs, and trying too hard - you open up that can of worms, you better be ready to eat it. Looks don't make much for conversation and really, if that's all a person has going for them then they'll be the first ones eaten if the survivors of the zombie apocalypse have to resort to cannibalism. Everyone else has skills, ya know?