My pack leader Sophie takes good care of me every day, getting those nose and eye boogers I can't get to, and giving my ears a good swipe. I return the favor for her. Boxers are known for their cat-like fastidiousness, and I often lick my paws and clean my own face. But it's s-o-o-o much nicer when Sophie does it.
I try to do it to my DogDad, as a mark of my love, and he apparently does not care to be thoroughly face and ear-washed by me, especially after I have loaded up my jowls with water fresh from the dog bowl.
Humans. I just don't get them sometimes.