Defining good comedy; you aren't asking the easy questions, eh? ^^;
I don't think I can give an actually useful answer. What made Monty Python good? Compared to Mel Brooks? Or Leslie Nilson? Or, I don't know, somebody like David Mitchell?
I can just say that when I look at a fantasy scene and there's no internal motivation as to why it's plastered with a meme, or a dialogue that suddenly veers into comedic tone with, again, no specific motivation then that's cringe to me, not funny (and in fact most of the above are at their best when they are being dead serious. There's rarely forced comedic tone).
Personally I'd question whether comedy should even be attempted. I get the impression a lot of creators (I'm speaking in general terms now) kinda go, "well, it's a porn game, it's not exactly going to be GGR Martin (< insert thematically appropriate author you like), so might as well make it funny". In a sort of implied "that's easier". Unfortunately if you aren't trying for Martin you are then accidentally trying for Pratchett instead. And who'd be convinced it's easy to write a Discworld book? ^^; In that regard I'd rather have authors tone things down a bit, make it lighthearted alright, but stay about there.
The other thing is ... again, maybe just me, but when I want to read sexy stuff, why would I even want to laugh? That's not exactly sexual to me ^^; So even if somebody did succeed I'd wonder whether a porn game is the right place for that.
But if it is done, then I can definitely say that "meme"s aren't good comedy. There's nothing witty about, nothing creative; there's no interesting setup, and no surprising (but possibly insightful) punch line. And I certainly don't want them stuck in a fantasy setting (unless there's good and specific reason to it).