Honestly, if a book sucks but it's on a subject I dig, then I usually have a blast reading it anyway XD I think it has to hit a certain sweet spot, though. Like, it has to be: "Whoa, everything about this plot is right up my alley. It SHOULD be my favorite story ever. But it's written so badly that it's not effective at all." Just any old dull, bad book won't do. Plenty of terrible Star Trek books out there for example but only a few that bring me genuine pleasure to pick apart.

It's the same with bad movies. I used to drive my ex-wife crazy hunting down awful 80s horror movies to watch before work.