Not that I’ve read? I think it’s very much ‘uploader’s choice’. 
I think the only obscure-ish rule is that it must be who you claim it is (so you or your partner(s) with permission). And I think that’s more to do with copyright? (Though I’m not that hot on the photo rules).
ETA: Though reading it again it’s about photos you own. So not sure the interpretation above is correct?
Yes, that’s more the area I was thinking. I should have said airbrushing, but I’ve not heard of ‘liquifying’ before. I think I could use a bit of that myself. 
I suppose more natural ones would be helpful with the LH lingerie shots so people can see the fit? Though arty photos are nice, and I bet they need a bit of work.
I think this may need its own ‘If WillC’s Radiator had a Profile what would it say?’ topic.
I think it looks like a Harry.