Well, I haven't done any escorting (I don't feel confident enough about my boobs for that) but in other areas of business it is common sense that if you want to use someone as a reference you ask them first.
I just spend an hour of my Sunday on phone giving a reference to one of my ex-underlings. That's time I could have used differently for important stuff like for example watching porn, but he had the common sense and manners to call me yesterday and ask nicely. He was considered for a new position and urgently needed a reference.
If I instead would suddenly just have got the phone call from the potential employer tonight I would in best case told the caller I'm busy and in worst case that I'm not interested to give any referrals.
What everyone should understand is that when you ask for a referral you are asking the person to put his/her credibility and reputation on the line for you. So ask before, ask nicely and say thanks afterwards! [/end-rant]