I assume you are referring to ads with providers that don't have reviews, so with those...

I personally avoid ads that have very young looking provider pics (i.e. those that say they're 18+ but look younger) - I think LE really wants to nab the johns looking for the youngins... which they should in my opinion.

I gravitate toward safe-by-association ads (i.e. ads that I can link to other providers I've seen by location, etc)

I normally see only massage providers so my risk is a bit lower since I can always refuse the extra services if it does not feel right (as long as I didn't implicate my intentions in the appointment setup phase).  This approach does not work for escorts.

I agree that the diamond in the rough hunt is appealing, but it's risky business and is probably just a matter of time before you run into LE.  This is why 99% of the time I see reviewed/trusted providers