I don't know if it's a fetish as such or even much out of the norm but I mentioned something on a thread very recently about how arousing I found it when I saw a random guy checking out DW when she was sunbathing nude at the naturist end of a French beach a few years ago. I was just walking back up from a swim in the sea and I saw him walking towards her. I somehow just knew he was going to turn his head to have a look at her as he walked by (she's a very attractive woman) and he did, which I thought was quite funny predicting exactly what he was going to do.
But I was also surprised at how exciting I found the idea of this complete stranger appreciating her nude body. I mentioned it to her later and she laughed and was quite unbothered, but she also found it pretty sexy. Talking about it in bed later turned us both on and led to some amazing sex.
Around about the same time back home we watched the French film "La Belle Noiseuse" (there's a French theme going on here somewhere!) about a man, who is a young artist, and his girlfriend who are on holiday in a warm and beautiful area in rural South of France, agreeing to let an an older established artist, who is redisovering his muse, to paint her in the nude in his barn studio. It's a great film by the way, not actually about sex at all but the power of art. It won a number of awards I think in 1991. It's well-worth seeing, with Jane Birkin as one of the characters.
Anyhow, the man leaves his girlfriend, totally naked, for hours at time with the artist as he works on his picture.There's no sex btw and the artist is just interested in her as a subject but the fact is that he sees every part of her body as he looks and sketches and then paints her from different positions and angles.
The idea of DW doing something similar I sometimes find hugely erotic, especially in a beautiful rustic French setting like that. It's something about another man seeing her totally naked and her enjoying that, even (maybe especially) if I'm not there but just knowing it's happening. I'm definitely not into the idea of her having sex with other men by the way, it's just other men seeing and admiring and maybe being turned on by her naked body and her enjoyment of that that I find really arousing.