Disclaimer off the bat, I am no expert on the subject. However, IIRC, I read or watched something about this one time a LOOOONG time ago. Given small wounds like scratches, your own saliva can actually be beneficial to begin healing the wound. Have you ever scratched or stuck your finger and instinctively put it into your mouth? That's what I'm talking about. I don't think this would apply to larger wounds and certainly someone else's saliva in the wound creates a host of other issues. FWIW.