Ignorance
I don't like to associate with people who have racist, homophobic or general prejudiced views or thoughts.

Lack of manners
Okay, I don't expect a guy to constantly open the door for me (even though it would sometimes be nice), but I'd much prefer it if they had general good manners. If I were out on a date with a guy in a restaurant and he was impolite and rude to the waiter, he would be kissing another potential date goodbye, and not me!

Bad hygiene
Need I say more?

Extreme high maintenance/vanity
Sorry, but I couldn't date a guy who spent longer getting ready than me for going out! I also generally don't go for guys with rippling six packs; they don't appeal to me, as they scream vanity and obsession with the gym (MOST of the time). I like it if a guy takes care of himself, but NOT excessively to the point of make up (guyliner, manscara... seriously?!), fake tan and hours of hair styling.

Immaturity
Again, it goes without saying.