Its a way WGs have found thanks to A/W of making more money and help line A/Ws pockets as well of course. Some WGs may well think its worth the risk of only showing a face pic if the punter has paid for the privilege, as you say who knows what could happen to that or those face pics though. A WG that concerned simply wouldnt supply face pics at all in my view.
I just don't think a face picture is particularly incriminating, if taken out of the context of adultwork, i.e. supplied by email.
Anybody can get hold of picture of anybody these days (off social media or whatever). Just because I have a face picture of somebody and claim that she's a prossie doesn't constitute proof. That's my feeling anyway.
I agree that a face picture anywhere on an adultwork profile is incriminating, but those within private galleries are less likely to be seen by simple nosey-parkers.
I'd order pictures in the following way, in terms of incriminatoryability (it's a word
Verification picture (i.e. identifiable picture plus holding an AW card) > identifiable sex picture > identifiable nude/part nude > face picture on adultwork > face picture via email.