The numbers do seem off. In San Francisco there are quite a few legit strip clubs many operated by Deja-Vu - they also make $$$ from real estate as they own multiple properties in North Beach (Little Italy)under shell companies like BSC Management. I did marketing for many adult companies and have a friends who worked at clubs in various roles from managers to DJs, dancers to maintenance. There are a clubs where the girls will offer "extras" in private booths and these clubs are well known. The amount that the girl quotes for oral ($400) means that she charged the guy $600 or did she just make $200 after paying the backroom fee? It's not clear but either way that is expensive for that particular "extra". Maybe those are Manhattan prices but in SF $400 - $600 will get you "full service" at the most expensive club. It just seems to me that with the size of the crowd and amount of girls that the club income would be higher. The other thing about SF is that the cops leave the "extras" clubs alone but they do target the regular clubs and if there is any prostitution going on in one of those clubs they do make arrests and suspend liquor licenses etc...
You can find out more about the San Francisco club scene here...

http://forum.myredbook.com/forum/DCForumID11