If you have like a scratch inside your mouth or a cold sore and it is still open at all you run the risk of catching HIV or any other STD. Peace
I use a condom if it's not a long-term monogamous relationship. You gotta be careful! It's a low-risk activity, but I'm not messing around with my life.
Well, I usually get to know the person before I let them do something like that. And I always ask if they've been tested. I think some don't affect the mouth, not sure. And the only one I can think of in the mouth is herpes, which is half the time visible. So getting to know them first keeps me from gettin' paranoid. Sorry, it just doesn't sound pleasurable at all with a condom on.
You can get AIDS whenever you have any kind of body-fluid exchange between two individuals. If one is HIV+ or has AIDS and you exchange body-fluids with that person - you can get infected. So be careful!
