is it considered bad form to request cbj from a provider who offers bbbj?

I wouldn't think so.  I have encounter providers who did not like to give them because the latex either irritated them or tasted bad.

Is there ANY way to do this so that the lady doesn't feel offended and like you think she is dirty? I don't personally think so. Why not just find someone whose thoughts on safe sex match your own? For me it would completely ruin the mood and destroy the session, I would feel awkward and unhappy and like you'd rather be someplace else.  

For the ultimate in safe sex, check out realdoll.com... those girls are *never* offended no matter what you do!

Best,
Tamara

ask the right way, and maybe provide flavored protection

ladies that play "safe". Just read the reviews until you find one. It may be offending to a bbbj lady as she make think you are suggesting she is "dirty". This is not to offend ladies that offer bb services.

I don't think it's ever bad form to request what you desire.
I would suggest you be completely up front before scheduling, however. Say something to the effect of, "I prefer to play completely safe." -if she doesn't understand what that means, it might just be best to move on to a wiser lady.
If she is willing but hasn't done it previously, be sure to advise her to use condoms without a spermicide or lube - those taste mighty nasty. Bring along an unopened pack of your own so she doesn't have to buy a whole pack just for you, if you're feeling generous.

It's your health concern that you ask for CBJ, not the concern that you may offend her by suggesting she is dirty.  I think most providers realize that bbbj carries health risks but do it anyway under pressure so you won't be offending them. But you do have to respect and accept her refusal to provide BJ on lub condoms because they taste lousy.  I am like you always ask for CBJ but sometime end up not getting BJ at all because she does not carry non lub condom.  Carrying your own brand of condoms is out of question if you have a spouse.  A better alternative is look for CBJ only providers and they are the safest providers on earth.  CDC has clearly identified that unprotected oral sex carries STD risks though HIV is of the least concern.