This is pretty far down the list, but my complaints have to do with professionalism. For example, facials have become a staple of blowjob movies in part to "prove" that sex is really going on, and most porn photographers aren't competent or experienced enough to film a swallowing episode well. Likewise, when there is a 20-minute "cruising" scene (like every Bang Bros video), it means that whoever edited the video didn't know what he was doing.
A mild defense of Ron Jeremy's later work--Anybody who buys one of his videos knows what he's getting, and there really is something mildly charming about his "Oh, I have to fuck another spectacular model" attitude. I suspect that by now it's a really hot experience for Ron to fuck somebody without a camera and lights in the room.