Guys,
Pacifica is correct. Fortunately, the risk of contracting the HIV is very low from cunnilingus.
Of course, there are numerous other diseases one should protect himself against. These include, but are not limited to oral gonorrhea, herpes, chlamydia, and the common cold.
How to protect yourself: Best method is to use a barrier, either a dental dam or a piece of plastic clingfilm, like Saran Wrap. I know, I know...it just ain't the same. Okay, say you want to eat her bareback. Do the following at a minimum:
1. Avoid brushing and flossing your teeth an hour before making contact. Small wounds and tears in the gumline can provide a path for transmission of bacteria and viruses.
2. Rinse your mouth with a strong antiseptic mouthwash such as Listerine for 30 seconds (no violent swishing) before, and again for a period of not less than 30 seconds after dining at the Y.
3. Do a visual inspection...but be aware that many illnesses have no externally visible symptoms. Even herpes can be contracted *before* the cyclical lesions appear.
4. Please disregard all the old wives' tales and bullshit. "If it smells like fish, eat all you wish, if it smells like cologne...leave it alone." Nonsense.

Finger test? Proves nothing. A friend of mine swore you could take a dab of your own ear wax and place it into the vagina, and if the chica experiences pain, she's diseased. Where the hell did the brother learn that? Inform yourself.
Confession: I have eaten many, including Pammie at ZB. No illnesses two years after that particular contact. Maybe I've ducked 87 bullets.
Either way, be careful!