Some nudes just look naked.
I think you can always see the intention and whatever thrill the artist was getting in the actual art. And then there's the thing where if you know the artist is fenale makes you feel differently than if it were a male artist. Which is bad but true. I think whenever you can't decide, think how the exact image would look with a male nude instead of a female and if you get a funny feeling in your gut, you know. UMS 'chops' frames to size, but not plexi.