Is it true that it's really very difficult for someone to contract hiv from giving a bj?

Difficult to say: What will put you at risk with oral sex is if you have any open cuts or sores in your mouth. Keep in mind brushing your teeth and flossing cause microscopic abrasions and cuts. Now having said this..Its difficult to quantitate this type of exposure. No one can give you a specific % really. The risk is certainly lower than vaginal or anal.