Several:
1. The choke hold, while I rarely watch straight porn I don't like it when a man does that to a woman, man or other genders.
2. Spitting on the hole more than 5 times over and over.
3. Dribbling during oral.
4. Tattoos and I apologise as I know many are into them these days, however there are some exceptions namely Colby Jansen, Johnny Hazzard, Landon Conrad (I know he has not many), Logan Moore and Buck Angel (I know his politics and views upset but just doing this for list).
5. The rose bud there is a medical scene if I remember one day I may post, but this guy has something stuck deep up him and the hot bearded doctor gets it out and decides to rimm and the guy pushes his anus out and the doctor licks it, but that is only for a second.
Again, if anyone does these things or has tattoos it's cool it's just not my thing those 5. I'd add being pissed in the mouth which I refuse but being urinated on is hot.
5.