If you're a serious admirer of canines as a species, then not many things can be more sweet than a happy, friendly doggie licking your face enthusiastically. Aww. "People licking" can be an expression of pure affection and admiration, but can also be a pure expression of canine subordination, too.
Display of Affection
A dog licking a person can indeed be a sign of genuine affection. If you're sitting on the sofa enjoying a relaxing evening with some popcorn and a few comedy DVDs only to have your tranquility "disrupted" by a happy dog licking your face, then you can be pretty sure that your pet loves you. The little guy perhaps may be looking for a little bit of undivided attention courtesy of yours truly, too.
Declaring Your Dominance
A dog licking a person may also have a slightly deeper meaning than pure affection. If your dog licks your face, he may be indicating to you that he is aware of your higher status. Your fluffy pal is essentially communicating that he is your subordinate and you are in charge of him. He does not consider himself to by dominant of you in any way. This licking behavior isn't only done toward humans. A dog may lick the face of a "superior" fellow canine, too.
If your dog is still in the midst of the puppy stage, then his licking of your face may be a demand for yummy food, pure and simple, whether a can of chicken, some tasty treats or whatever he sees you eating at the dinner table. The licking is basically your cue to head over to the refrigerator or cabinet and give Junior exactly what he wants.
A dog may also lick a person -- or another dog -- as a way of encouraging "peacemaking." If your pet is worried that you may be unhappy with him at the moment, he may try to extend an olive branch of sorts to you by giving you a big, sloppy and wet face licking. If you notice your dog rigorously licking your face right after he got caught chewing on your work shoes, you may know exactly what is going on.