Well, intelligence, self-confidence, and self-motivation are the things I find most attractive, so I would say the inverse of that are the things that I find to be the biggest turnoffs.
It bugs the shit out of me when people pretend they are dumb when they are not. You know that fake dingbat thing that some girls do? That never made any sense to me.
Also, laziness and sitting on your ass all day, as well as not believing in yourself. None of this has anything to do with the physical appearance of somebody.
You can be physically hot and be lazy, pretend you are a dingbat, and not believe in yourself, and you’d still be very unattractive in my opinion.