I've come across a few gems as private MLs. I think this is the criteria by which you can tell theyre not fake or are at least in with a chance.

1) Photos to prove what they look like, with phone numbers, wchat. The pictures have a brisbane landmark in the background.
2) If they advertise they are young and hot but really cheap, avoid.
3) Some of the websites will have a "other adverts by this user" function. If the pictures are different, she's a fake.
4) google her phone number. If you notice also the pictures are different, she's a fake.
5) Search the advert title, particularly the name, in that website and others, if pics are different, she's a fake.
6) If she says she's a university student, here to study, but fails basic english and grammar skills, she's fake.
7) If she claims to be japanese and other adverts with her name/phone number states a different country (china usually) she's fake.

Feel free to add things youve noticed.