The thing with deal-breakers is that in my opinion, they're oftentimes very difficult to weed out as with many issues, it's not so black and white or obviously apparent. For example, a huge pet peeve of mine is people who treat servers in restaurants, or really anyone in the service industry, poorly. However, that's not something that may come out in a first date or second date. There are a few things that are pretty black-white with me that I can think of that you can find out right off the bat:
Smokers - I'm allergic, and just think it's dumb, although I sympathize with those trying to quit.
Drug users - I don't want to become close to someone who does something illegal. And yes pot IS a drug.
Republicans - No. Just no.
Then there are personality issues that may take awhile to surface that I find unattractive and that will cause me to bolt pretty soon after surfacing like:
Monogamy issues - If a guy tries to cheat WITH me, there's no way he'd have a future with me. Similarly, any guy with a history of cheating on past boyfriends is out of the picture.
Abuse - That should go without saying. Any hitting is out. Verbal abuse can be a bit trickier to define. I was involved with a guy once who would make these subtle digs at me and I will never expose myself to that again.
Drama queens - I HATE drama. So many people seem to really flourish in it and that is not me.
Mean people - There seems to a belief in this world that you have to step on people to get ahead and what you want in life. I don't buy it. Don't cuss out a cashier for ringing you up too slow, don't snap at a waitress because she's moving slow, don't take out your personal anger on your co-workers, etc.
Very religious people - As a whole, I find religion to be a very personal thing. I do not personally believe in the concept of organized religion but have no problem with those who do; however, the fundamentalists who judge and feel the need to shove their beliefs down others' throats, does in fact bother me.
Guys who's sexuality defines them - I've met some guys who are just ALL about being gay. Conversation is constantly about this celebrity being secretly gay, or how there's a Pride parade next weekend, about the gay club they're going to that night or constant sexual remarks relating to anal sex, and stuff like that, and it's just a turn off. It's great to be comfortable and proud of your sexuality, but all conversation and activity doesn't have to revolve around that. A person's sexuality to me is just one part of their identity, not the entirety.
Lack of a sense of humor - What's the point?
Vulgar - I met a guy once who within moments of meeting made a joke about his "mom's pussy juice" and then followed that a few minutes later by making jokes about pedophilia. I'm not a prude by any means, but stuff like that just makes you sound immature and uneducated. Ditto for guys who curse every other word.
Materialism - If you like fine wine and designer jeans, that's great and fine, provided the fact that I drive a Ford Taurus and wears jeans and a hoodie and prefer pizza, doesn't cause you to have an seizure.
Lack of world knowledge - I don't think I have very strict criterion with this, but I mean, you should know where France is, be registered to vote, know that they don't live in igloos in Canada, know who the President is, etc.
I don't know. I guess this latter list is more pet peeves than surefire deal-breakers, and they're really no different than most people's i.e. I'd like someone kind, somewhat smart, with a sense of humor and non-judgmental.