Yeah, imgur must have all the NSFW content hidden from their own search. Anyone who knows how to use Reddit will know where to find the NSFW stuff they've swept under the rug though, so I'm surprised that's enough for Adsense to give it the OK -- Reddit users are probably 90%+ of imgur's audience.

Maybe you need to do the same thing: set up an "un-affiliated" website that allows you find all the 18+ content on Twicsy, haha