Cruel to animals/humans/life
Dishonest/untrustworthy
Lack of aspiration/goals
Smelly like after-asparagus pee
Ownership of a real penis (attached or otherwise)
There are other things but that's what came to mind.
*hides asparagus*
*throws penis out the window*
Oh wait... you said real
*sighs* ... dammit, cars are coming
Say it isn't so!
*is unfamiliar with term, Googles it*
Boring: This is very subjective and I'm sure many who I've found boring feel the same way in return. Still, if I don't feel that spark of interest in a person then there's no point.
Willfully ignorant: There are always going to be areas where you're somewhat ignorant in. There's too much information out there to know something about every topic. However, when someone wants to remain in the dark and does nothing to change that, any attraction I might have felt will be lost.
Needy: Nothing turns me off like neediness. You try to smother me with affection and I'll smother you with a pillow.
Not understanding that I'm a higher life form and you need to cater to all my needs: This is my biggest deal breaker, it's so simple yet so few people get it. A shame, for them that is.
Lie. You love my smothering.
Tomorrow I'll use an old plastic bag used to transport onions.