Everything I had to say in this thread has already been said, with the exception of the following.
Prefaced by the fact that I am neither a doctor nor expert on female reproductive systems, I am the owner of a vagina. According to one "Dr. Oz", amongst others, the va-jay-jay is a self cleansing organ (NO douching!).
It's the one hole men don't have and, yes, the moisture ends up somewhere. It ends up in our underwear unless a pad is involved (for most of us that's when Aunt Flo is around). My point is that, even though I think the wife in this situation is/was suspect, visible
anything on BLACK panties is NO evidence that some other guy has been there. Then again, I don't know because I haven't been in that situation in 21 yrs.