My grandfather saw me do this to a book once and told me the story of an Eastern mage who avenged himself by leaving the king who beheaded him a wondrous book with pages stuck together - but they were poisoned.
Never did this again...
I see no reason why bacteria can't survive like this.
I've found that breathing on my fingertips is enough to get a grip on paper. I don't actually have to lick them. I'm not sure if breath is much more sanitary than spit though.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.