for me, the difference between art and p*rn is (this'll sound a bit obvious) the intention behind it, and I think that the intention 99% of the time is pretty obvious in the image itself. You don't have to talk to the artist or get an explanation; the picture itself is a message, and when it's p*rn, it says, "F*ck me." All the tasteful nude pictures usually celebrate the female body. Not only are the women in the picture beautiful, but they are posed and presented in a way that accentuates and adores their beauty, in a way that puts them above being mere sex toys (like the covers of FHM etc are) and into the realm of goddesses. Documentary/National Geographic type pictures, fall in the middle; they just record, their message is pretty straightforward.
Recently there were nude photos of Snejana Opnoka posted on the web, from her less famous days. I find her so beautiful and not at all like a provocative p*rn star-esque girl, but those pictures of someone who usually appears classy were definitely pornish. They had the feel of, "I got a girl off the streets, got her naked, took some pictures, and then had sex with her because she was too young to know better." Not all nude girls in bathtubs are p*rn, but it's kind of like the difference between "we made love" (usually a cliche phrase, but couldn't think of a better one) and "I did that stupid ho."
I think the people on tfs, at least the registered members, are smart enough and mature enough to view nudity, in whatever form. We're not provoked by a nipple here and there, probably because we see so much of it in fashion as it is
. I'm kind of on the shelf about allowing requests for nude model pictures on the thread, because I know my fellow members can handle it, but maybe not some random person on the internet. Although, one couldn't request the pics if he wasn't a member, so perhaps it's okay.