Mond likken

" Greeting – We like it so we encourage it by laughing and interacting in a friendly way with our dogs, and our dogs learn to do it more.  Nothing wrong with this!
To Get More Space — Most people turn their heads and move away when a dog licks.  Lots of videos showing dogs licking babies can be interpreted as the dog trying to encourage the baby to move away a bit, especially when there is a bone or toy involved.  Jennifer Shryock of Dogs and Storks talks about this in her Kiss or Dismiss blog post and with more examples here.
Nervous, Anxious Habit — Sometimes the dog just doesn’t know what to do and reverts to puppy licking behavior when he’d probably do better with some space or human guidance to acclimate to whatever’s going on.
General “In Your Face” Behavior — Before going to someone’s house for a training session, experienced dog trainers know to ask, “So, how might your dog greet me when I get there?“  When the answer is, “Oh, he’s really friendly.  That’s one of his problems.  He’s just too friendly!,” we know to ask more and be prepared for an overly-aroused dog with little or no self-control.  Just because the dog is licking doesn’t mean he’s not also being a little too pushy and disregarding of personal space (see below).  There are better ways to teach dogs to get our attention.
Getting Food! – Much of the time, babies and toddler have something tasty (to dogs, at least) on their faces or clothing and that’s what the dog is going for.  One family I worked with had a dog obsessed with baby spit-up that would dash right to the baby’s face to get it fresh from the source. "