I was pretty concerned about this when I started out, especially as the CDC site lists a lot of STD risks from BBBJs. However, they don't specify probabilities for a given STD (other than that there is almost no risk of HIV) from BBBJs. I consulted a public health expert on STDs who suggested to me that contracting an STD from a BBBJ is generally pretty low risk. The greatest risk is Chlamydia, which is easily treatable - a single dose of
azithromycin. Gonorrhea is most risky when there is contact with the throat, as the infection thrives there more than in the mouth. So deep throating increases that risk (though I think a lot of people with smaller than average dicks conflate deep throating with getting it all the way in the recipient's mouth). Gonorrhea is generally also easily treatable (unless one catches an antibiotic resistant strain, but those are rare, especially on the East Coast). Genital herpes is a risk, but with that you mostly need to make sure to avoid BBBJs if you see any sores on the provider's mouth.