Not so sure it's as clear as that.
You can run your ad for "escort", but if a Vice Detective responds to your ad, meets the escort and she offers him a blow-job for $100.00, you stand a good chance of going to jail. I've paid attention to some of these services, Las Vegas in particular, and the whole staff has to be very disciplined in how they communicate every aspect of their business. In one sting, LVPD Vice had a fake "prospective employee" interview for a job while she was wired for video and sound and the sting came down on the woman that did the interview because she said something that implied a contradiction to what was explicitly stated.
A slight mistake at the wrong moment, and you are in big trouble.
I play with this idea too, mostly as a fantasy than as a serious business proposition because I used to live in an apartment next door to a bunch of strippers and let me tell you, if you ever want to have your entire life consumed by a shrieking and wailing maelstorm of of HIGH DRAMA and OUTRAGE, the HIGHS, the LOWS, the CRYING, FIGHTING, some drunk whore standing in the middle of the front yard in her bra and panties screaming at the top of her lungs "YOU JUST WANT TO FUCK ME IN THE ASS !! THAT'S ALL YOU EVER WANT !!! (neighbors lights coming on) YOU ONLY WANT TO FUCK ME IN THE AAAAAaaaaaAAAAASSSSSSS !!!!"
There's the fantasy of being in close proximity to a bunch of whores, women who have figured out that they can convert the stench of that hole between their legs into cash, and the reality of having your every waking moment completely dominated by this self-absorbed, retarded and money-grubbing whores.
There's a reason why pimps beat these bitches.