I posted this comment on a Victoria thread, but it's also relevant here:
"I feel safer getting a BBBJ from an SP than from a random girl I meet at a bar or nightclub. Escorts usually ensure they don't pass anything to their clients and risk losing them as repeat customers. Also, the agencies in Victoria have regular testing for their girls. It all comes down to common sense when accepting this service from an SP - if I notice something I don't like, such as a sore, I will not accept uncovered oral, but never had cause to turn it down in two and a half years visiting escorts. It's also the same for the lady offering the service; she won't do it if she feels it won't be safe - that's where YMMV comes in.
"A BJ is an essential part of a session for me, but it doesn't have to be bareback, which is why I don't pay extra for it (if it's offered 'on the house', great; if it's not, also great, especially if the lady knows what she's doing). I have never had a BBBJ outside of a relationship, except with a provider, and I've never contracted an STD in my life. I also hardly engage in DFK and I'm not into DATY.
One Dr. Hunter Handsfield of Seattle, WA, a specialist in infectious diseases, seems to think that uncovered oral is fairly safe. His response to a question is a little further down the page. A click on his name will reveal his credentials":
http://www.medhelp.org/posts/STDs/oral-sex-question/show/2159728
And to add: I would never accept BBFS from a provider, even if I've seen her 30 times before she offered it to me. That's just ridiculous.