To wander back to AnArdvark's comment, I think it's not so much that there is one low rating in a large high rating set, it's just that they leave a rating that shows that they feel that there is room for improvement, without making suggestions about how to improve, or even what it was that they didn't like about the image. I had someone complain about my light a while back, and I really appreciated it, because it made me think about how I was using light and what I could do to get more depth and be more creative with it--I ended up learning a lot from that comment, and am still learning. To use the rating system without using it for helping another artist improve seems..well, maybe a little lazy at best. If someone doesn't like nudes, or thinks an artist is in a rut, they should be able to say so--most people can sort through the personal taste issues, and sometimes too many nudes can be a kind of laziness too, because it makes for easy hits (guilty;-)  It's true that Renderosity tends to be a supportive environment because people come here more to share a hobby than to be professionally crit'ed (cg talk is the place to get your ego trashed, in a tough love way), but some criticism can help even a hobbyist get more out of the hobby, if it's done in a constructive way. I think that is what the rating were intended to facilitate--that kind of conversation.