I'd say most of the profiles on VS use stolen pics but there are of course some gems. I have been reading quite a few reviews from UKP members who have had success on VS and it has peaked my interest somewhat, but these days I'm less likely to TOFTT as I'm punting less than I used to and as a result value my spare time more.
Generally if it looks TGTBT then it probably is and there are image search sites like Yandex that can help determine if the pics are of someone else. Bear in mind that it is also possible to steal videos, so don't believe a profile is legit if they have one.
I've only had 2 punts from VS and both times the girl was the advertised one, but I guess I was lucky, both of these were a few years ago now.