Run the pics through
tineye or
Google Image Search. If they come back with ANY matches, she's full of shit and for sure a bait-n-switch.
Run her phone number through google. If anything other than local hookup ads pop, she's full of shit. If reviews pop, she's likely legit.
Any reference to her being a "stallion" or "[insert color]-bone" (Ex: red-bone, yellow-bone, etc.) and she's being pimped. Women don't talk about themselves that way.
Sequential ads with similar posting style, for example similar headlines, similar language, similar disclaimers, etc., she's being pimped.
Don't be fooled by "professional pics". Sometimes these ladies will trade service for service and have some very nice pictures. Instead, look for pics that have too much "wow" factor. If you find yourself saying, "Holy shit, a girl this hot is slinging pussy?", you're being dumb. Of course she's not that hot.
That's what I can think of off the top of my head. If I think of anything else, I'll add it. Be cautious with BP. I don't subscribe to the adage alot of these guys will and say that everything on BP is a waste, because that hasn't been my experience. But you have to be careful and selective, or you'll waste alot of hobby-coin.