Past sex history and doing oral to a girl?

presence you are talking about DNA right? With that there is none unless you was right there while it was begin done lapping at the juices as they flowed. There is nothing but a mental image with her and you know it took place. It would be the same thing had you put your penis inside a dozen other women and then her, there is nothing of those other women on you manhood. Now if maybe there was some kind of STD then one is subject to this. That stuff just not wash off from periods or soap and water wear and tear it is there to stay until medical intervention take place. There are a few that they can't even do anything about HIV for one. You are pretty much toast once that gets a hold on you.

Well, if she's had sex, you will be licking the place where another guy's balls have been, and if you have philosophical objections to this you're better off looking for a virgin.

But it is a myth that a guy leaves his "presence" in her vagina. The vagina is a very clean part of the body; cleaner than the mouth, for example. It constantly sheds cells in order to keep itself free from disease. So there is no detectable trace of sex in the vagina if it's been more than a week or so since she's had intercourse... usually much less.

Presence? What? No honey don't worry, there won't be any "presence" unless the guy left an STD or a baby up there.

She is correct. She is not forever marked by his 'presence' as you put it. There will be no trace of him inside her and assuming she has washed since sleeping with someone else, there will be no trace of him outside her.

its ok licking a guys sack isnt that bad