1. PoV porn. I know there are people out there that like this, but FFS, there's only so much you can just look at the same thing over and over with no variety.
2. Too much kissing. A little bit is fine. When it carries on for 5+ minutes of a 15 minute scene, it's too much. Also, on that same theme, when it's too dang loud. I'm sorry, but I don't need a kissing scene to sound like a pneumothorax correction surgery on an episode of Real ER Stories.
3. Fake noises. All of that grunting and screaming is annoying, just stop it.
4. Worn out porn clichés. I would rather you just shoot a scene and not try and put some ham-handed "story-line" to it.
5. Overproduction. None of the porn produced out there is by fucking Spielberg, or Scorsese, or Nolan. Just shoot the damn scene. Special effects and bizarre camera angles do nothing.
There are more, but I'm too tired to continue, LOL