Most ass-related stuff but particularly analingus and creampies should stay in the realm of 2D art IMO, as much as I appreciate nice butts I hate it when a picture focuses on an overly detailed or gaping anus or a guy getting stretched painfully; oddly I don't have the same issues with "normal" anal penetration or guys playing with regular-sized dildos. Similarly deepthroating is unappealing IRL (I'd prefer to date a guy with a smaller-than-average penis because I find them cute and they're easier to suck) and I absolutely love foreskin both in 2D and 3D but when foreskin play emphasizes smegma or strong odors that just ruins it for me.