I've been told by a few pornstars that they get MANY clients from the agencies who are not even aware that they are meeting a pornstar. Hard to believe? maybe, but it may go something like this (turning around and mussing up my hair, (if I had any) preparing for the impersonation)....
Let's use E2K... they are actually two agencies... Exotica and NY Elites. NY Elites has non-pse providers including many runway models, some off broadway actresses, etc., but there's some cross promoting going on for some of the pornstars.
A high roller clients calls them up and says "I'm looking for a lady who is wild in the room, brunette with big boobs... open to almost anything... bbbj dfk greek... send me the best lady you have who fits that description...
Knock, knock, knock... it's Anna Malle!
PSE's are a very small portion of the hobby, and there are a lot of guys out there who love to meet high priced escorts who have never seen a porn video...
Where we serve a valuable service to not only fellow hobbyists, but to the agencies as well, is when we see a new provider and review her. after a review, the agency knows what the girl is like, and can go on to recommend her to a client who doesn't necessarily ask for a particular lady, just a particular type.
Believe it or not, the agencies can be just as clueless as we are regarding what the girl is going to be like on her first tour. Take Belladonna for instance... we all have expectations, based on her videos, but these agencies aren't fans of porn... they don't watch and analyze the girl's movies and say "Hmmm... I think she's what we're looking for"... they hire based on who they can get, and how many requests they've gotten for her, and they might not even meet the girl before she arrives in NYC for her first tour. And it's pretty awkward to say to a girl... do you swallow? Do you take it up the ass? Besides which, the agency doesn't really care if she does or doesn't. "Belladonna? Shit, we've been getting 20 calls a day asking if she's available, now we've got her". They don't care if she just lays there like a bump on a log; they're going to sell her bookings out, at least the first time... they'll worry about her reviews later.
So the answer to your question is yes, readers of these boards are a very small percentage of the agency's clientele, and truthfully, we're for the most part the one or two hour guys, not the full-evening-dress-her-up-take-her-to-the opera-then-back-to-the-room-for-a-good-night-fuck kind of guys, which is what the agencies all really want.