I assume you are speaking of Backpage and boards like them.

Not that all ads are bad but much more research is required.
IE. No reviews from a 21 year old Smoking HOTTIE because she is new to the area. LOL

The ads are fun to look at though.

you could post on your Regional Board when you see the ads are

Up . Explain your concerns to the ladies in your area too , the real providers. That may help , also under the ad pic , Write "skank above ! And a red smiley"

If there is, people would have done it a very, very long time ago. Only thing you can do is, use good judgement and don’t fall for it.  

Google and TinEye photo search and your ability to filter is your only tool.

I'm not sure how they do it, but it really helps the guys out. Perhaps you can do something like that.

You can't catch them all, but calling one out will feel oh-so-good!