Frankly, No, I find the Female Body absolutely Beautiful (well, in most cases, at any rate) and No, the sight of a Naked Woman doesn't disturb me.
Does it disturb you?
As for the difference you discuss, most Painter's/Photographer's Models aren't married to the Artists they pose for. So that would by default make them strange men they are posing for.
So, I guess the difference you're beating around the bush about is Male Arousal. If it's Nakedness that doesn't get your Knickers in a Knot, then it's Art, and OK, and you have no problem with the young Lady getting paid for services rendered. However, if somehow she causes the viewer to become Aroused, then she is the cause of the downfall of Society, and must be Labeled as such.
Can you say TALIBAN, I know you can...