A good parody game to me doesn't require you to have knowledge of the existing materiel to enjoy the game, references are fine but if the whole game needs a complete understanding of the original then I'm more likely to drop it.
Would you be more willing to do that for a game you've been following or do you just immediately drop a game once you realize you're gonna fall into the repetitive grind?
The main reason why I dont go for the harem path is because usually im not interested in all the heroines, not a big fan of games that force you into a harem with characters you might not like.
I dont know if this counts but probably condom sex, their is something thrilling about the potential for a condom to break or after a going through a box of condoms the heroine is laying their with a condom stuck in her and the rest of the condoms all over the place.