My cats are more hedonist than my dogs - so they're not much into kissing me. When they get on my lap it is for me to shower them with affection and they purr and let me love on them. I had one cat that would lick my hand until she almost took the flesh off (which their tongues are designed for).
My dogs, on the other hand, love, love, LOVE me so much that they will lick my face if they get close to it. When that does happen, I turn my face to wipe it off so they won't see me. LOL! I try to avoid letting them do it because I know where their mouth has been. Occasionally they lick my mouth and I kind of freak out, go get the Listerine.
Still, like others have mentioned - I've caught way more stuff off of other people than I have from my pets.