When a provider offers BBBJ , I understand loving it but do you guys get nervous or worry about contracting an std this way? Do you not go BB?

If you don't want to do bbbj, then don't.  It shouldn't be a prob for the providers.  Personally, if I can't get bbbj, I don't see her.  But, too each his own.  Do what you feel comfortable with.

Swim

The risk of fatal diseases like HIV and Hep C, Hep B is normally very, very low for bbbj.

You can get other things that are nasty but easy to treat like chlamydia, gonorrhea, syphilis
 or annoying but not life threatening like herpes and HPV.

Make sure you pee soon after a bbbj, it can reduce your risk of GC and chlamydia. Probably best to wait til your dick is out of her mouth, though.

And if you hobby a lot, think about getting the Hep B vaccine.
If you're young, consider getting an HPV vaccine also, your future wife will thank you.