No, I don't ask.
Odds are they'd lie about it anyways - putting 1hr VIP GFE 300$ (HIV POSITIVE) on EROS isn't a lucrative business adventure.

If I knew they were dirty then no, I wouldn't see them.



Regardless,
Don't be a fool, wrap your tool.

You ask her if she's been tested? Exactly how does that promote safety?

Do you really think she will tell you if she tested positive?
If she tested negative and showed you the document, are you that naive
not to realize that she can test today and get infected tomorrow?

Being absolutely safe no matter what means not having sex.
Having sex with multiple promiscuous partners is an unsafe activity.
The BEST you can do to protect yourself is to always wear a condom.
Testing provides a marginal boost in safety, but guarantees nothing.