Even though I haven't been there for a while, the tip sounds about right. Some girls want more others will take less.
But in my opinion, once you add up the "room charge", you can look on EC or even on this site at the SP's and you can get more mileage for your money. BUT having said that places like Broadways, Nevadas, and EB/TO (*My favorite of the bunch), are great if what you want is without an appointment to walk in, get off and walk out.