Ok, I didn't phrase my question very well ;-) I've not shot any nudes before so it would be a learning curve for me. A lot of Ian Leake's images (which I admire) are more about the naked form and don't include the "naughty" bits as it were. That's where the how nude is nude question was coming from. Does that make it any clearer?
Firstly thanks, and secondly sorry for not taking your question seriously (I blame Art - he's a bad influence - bad Art!).
In my opinion (which is just another opinion of course), nudes are just that - nude. Partially clothed models are not nude - they're partially clothed. I never work with partially clothed models, so even when I make a photo of someone's feet or their hand it's a nude. (Just to be a bit pedantic: none of my models are naked - they are nude. 'Naked' has a subtly different meaning to 'nude'.)
And, again just an opinion, there are no rules regarding what is or is not shown - faces, 'naughty' bits, eye contact, and scars are all up for grabs. Same goes for the model's sex. It's all down to what you and the model are happy with.
Hope this helps.
P.S. If you're looking for a model let me know and I'll be more than happy to recommend some.