That is what I do also. Relative information is what is the priority on a reference check. Just as the gentlemen say about us that it can vary from individual so can it vary from each encounter.
Posted By: Hmmmm............
I research the girl and find out who is asking for the info. Anyone can email and say, "Hi, I'm XYZ. Have you seen ____?". So for his protection and mine, I verify that she's a legitimate escort.
Then I may tell her a brief physical description (sometimes guys pretend to be someone else/ use their friend's references to see a girl.) So maybe race, age, hair color, height, etc).
From there, just a general run through of any problems such as bad hygiene, asking for BBFS, annoying behavior (calls too much, cancels frequently, etc)
If there are no problems, I'd say just that. No problems. Or if I really like him, I'd say he's awesome, or ideal client, or something like that.
Usually, guys are not a problem. And if they were, it's unlikely that they'd use me as a reference.
I don't typically give any personal/sexual info unless it's something really relevant. Like if he is abnormally well endowed, I just discreetly tell her to bring a certain type of condom. Or if he has unusual fetishes, I may mention that briefly. We do NOT talk about how you are in bed. The main concern is if you are safe, nice client or not.