I think it's up to you whether or not to use the nsfw tag (after all there's a lot of publicly accessible statues, sculptures and paintings of pretty much everything in museums and just around the place). I think I have mentioned to you before that if you don't hide behind the stupid tag though you have a chance of getting flagged by some prude who will cry because something you posted offended their overly delicate sensibilities :) (and this could be a problem if they're the type that like throwing their weight around)

However after thinking about this for a bit I think we should just hide behind innocuous thumbnail images and plaster warnings in the titles and opening paragraphs and if people go ahead and open them anyway then it's their own stupid fault ;D