Las Vegas
...she could be moonlighting (at a very inexpensive rate for a PS, and not under her PS name). I find it very unlikely (like, lottery odds unlikely), but it's kind of possible. (Some of the scenarios under which this is possible aren't good ones, mind you. I'll leave it as an exercise to the reader to figure out why.)
I sure as hell wouldn't see her unless we were meeting in the casino bar first. (It's a good way to avoid bait-and-switch, I find, plus it's the perfect excuse if you're in a hotel where there's security to pass before you go to your room.) People are unlikely to cause scenes in public if you say "I'm sorry, you seem to have mistaken me for someone else. I don't believe I know you".
That way, when the nearly inevitable "Oh, something came up, but my friend's willing to show up" call happens, you can say no on the phone and make other plans, like calling a well-reviewed independent (though your choices for short notice are more limited) or Bruce at Pretty Maids. And if by some odd chance you DO get lucky and end up with a PS for $400 an hour, more power to you. By all means, write a review. 