The problem I've noticed over the last few years is that a lot of the fake profiles are using pictures that they grabbed from some poor tarts facebook or instagram account. Facebook/Instagram don't let the pictures on their pages be web crawled, so they'll never come up on a reverse image search unless they've been posted on some other site too. It's making it harder to determine the fake accounts from the real ones.
My general rule of thumb is that if a "girl" on Adultwork is only using clothed pictures then there's a good chance they've been stolen from someones social media pages. Also, if they repost the same pictures in their galleries that also sets off alarm bells. Inevitably, a private gallery will appear with the face cropped or blurred so other more hardcore pictures can be used.