If a profile is legit?
I would generally steer clear of profiles on AW that are part of one of those "clubs", vivastreet in general, and/or have low feedback and minimal detail on the posts and gallery. Image search is also your friend.
Is she a he?
I've never really considered this as i can't recall ever having any doubts but given that as a species we are, in many ways, wired to detect certain things unconsciously and detect the uncanny without necessarily being able to articulate the uncanny, then I would probably say that if you have any doubt then maybe it's best to err on the side of caution and see a different SP.
Is she any good?
generally i would cross-reference AW reviews/profile with this website and take what is on AW with a pinch of salt.
lastly, if i were looking to answer all of these questions i would probably use the search function on UKP also. there is plenty of advice already on this forum that answers this topic in much more detail than above. for example; searching "how to spot" just now has provided lots of results on this topic.