Spit will not kill sperm.
Can A Female Get Pregnant If The Sperm Is Mixed With Spit?
I highly doubt sperm would die in spit. They are very strong individuals =]
Um..... I'm not even going to ask why the spit is down there. You guys are sick! I guess there's a little freak in all of us.. She should hurry and get in the shower and pressure wash her stuff or try to douche.