-Sexist
-Homophobic
-Racist
-Ableist
-Violent guys
-Manipulative guys
-Anyone addicted to drugs or alcohol and refuses to try and stop
-Rude guys
-People who take nationalism way too far
Those are the absolute worst in my opinion. As for others that I'm not awfully keen on, I don't like clinginess or overdependence, and I'm not keen on guys who sleep around a lot, it makes me feel like I'd just be another notch on the bedpost to them