Your question is too vague for the example you provide.
It is pretty much a given that a Chinese/East Asian ad is a B&S pretty much anywhere but moreso on VS. That's not to say that there isn't a lady behind the ad who isn't willing to offer a (good) service for the money.
There are other ladies from other nations and ethnicities listed who are sometimes the girls (deceptively) pictured and also offer services for the money quoted, but often they have a (lengthy) list of extras that are increasingly over-priced.
What do you mean by "genuine" and what services are you demanding for 100ph?