Face it, if sucking dick rountinely led to infection with HIV, the "gay community" as we know it wouldn't exist. Of course there is risk associated with sucking a dick and with swallowing cum, but it is a matter of relative risk. By now, you all know how to limit your risk (I would hope!) and it's a matter of what degree of risk you are willing to take. All said and done, sucking dick in and of itself is not an extremely high-risk behavoir. Swallowing cum, assuming you don't have an open pipeline into your bloodstream, does not significantly increase risk because semen and viruses are destroyed by gastrointestinal enzymes. Any "injuries" you might have to your mouth or throat or escophagus increase your risk of infection. It is generally agreed that it takes more than one exposure to seroconvert, so frequency of exposure, as well as degree of exposure is another consideration.