For me it's not a germ thing. I am not in any way a germaphobe, I hate someone's breath in my face and I am grossed out by someone's tongue in my mouth. Gives me the willies.
I'm fine with pecks but no open mouth and no tongue. I can't stand dogs licking me either. EWWWW
my rabbit licks my feet and legs, and that I am totally ok with because rabbits only eat nice green stuff, don't have sloppy tongues and I love my rabbit, so nearly anything he does is fine by me (he has his own bedroom).
I'm fine with kissing anywhere but the mouth. My last boyfriend wasn't a kisser either, so that worked out very nicely.
My daughter LOVES kissing and makeout sessions. We simply don't understand each other as far as that goes. I don't know where she gets it from.