When girls have tits that are so fake that they look like they are about to pop or are starting to "sag" around the edges. (ew)
I saw one scene where this girl was getting fucked missionary, and the way she was moving, you could see the implant going squish, squish, squish.
Otherwise, another vote for the spitting being gross. I've seen ones where the guys are spitting into each others' mouths....Yuck.
Also, felching/squirting. I find that gross. If you've shot your load inside, I really don't need to see it get pushed back out.
Over the top Dirty talk and campy moaning. I think that's just silly. I like passionate sex, where both participants are into it, but I don't need to hear "Oh Yeah! Suck that cock! or "Ay! Fuck Me!" yelled/whimpered over and over. I also don't need to hear the bottom/girl whimpering like a terrified puppy dog, or yowling like a catamount in heat.
Ditto with the fake and overdubbed sounds. I like to hear some sounds of satisfaction, but if it's not there, it's not.
Very violent sex does nothing for me. I don't need to see someone get smacked around the room or mock raped. Passion. It's all about the passion.
Conversely, I don't like to see someone laying there like a dead fish getting fucked. I also don't like it when you can tell that the participants are stoned out of their gourds. That is just gross to me.
Other than that, the typical piss, scat, puke and blood. Not my fetishes.