Poor table manners, I can't find someone attractive if they're a sloppy eater. It's not hard, chew then speak, Chew with you mouth closed...
Other major deal breakers:
Not being able to think critically, so close minded or gulible people.
Stupidity... actually no, not stupidity so much as being uniterested in learning.
Poor general health, I don't mind overweightedness, underweightedness, smoking, drinking, drugs the list goes on but I do mind obesity, dangerously underweightedness, chain smoking, alcholism, and being druged up 24/7. Well unless you're working on fixing your problem then it's more of a minor issue.
Other more minor deal breakers are:
Clingy people; I'm very relaxed about contacting people, I work on the idea that no news is good news, no news for a week might not be good news but news updates every five minutes is a good reason to change the channel.
Not sharing my sence of humour, imagine not laughing with the one you loved, it'ld be a bit rubbish.
Getting your opinion from magazines would be pretty bad too.
Okay I'm kinda going off and sounding really picky. oh well, at least I'm not too vain. And I think most people would agree with most of what I've put.