I don't understand why some guys still try to request/do this. They should know by now its not only risky but a big rule in the escort industry to not cross.
When it comes to escorts offering it, personally it never happened to me, and i hope it never does. I would say NO obviously but that mean she has done it with other clients and it would make me nervous. I know some escorts most certainly do it with there boyfriend or even personal fuckfriend, but i tend to hope for the best and think they have are being checked frequently and know each other are clean. In the end best way for me to protect myself is to always stay protected for vaginal intercourse.
I will admit tough that CBJ is not my thing, and i would be very disapointed if BBJ was not the norm anymore. But as some peoples said in this thread its less risky and from what i gather almost impossible to get HIV that way.
So if you are sure some clients try to do this, yes ban them, they should know by now its a NO GO. But i am also agreeing with Doc and Iggy here on one thing. Better be carefull this is true as this would quickly tarnish there reputation.