My Dixie is very licky. It can be annoying. I don't know why she does it but she stops if we tell her. She will also lick people on command!
Sometimes she does it, its almost as if for attention, like if I'm at the pc she will walk by and lick my arm. But she doesn't stop for attention, she walks by. Kinda like she is tasing me to make sure I'm still here!
Dave isn't licky. Thankfully- his tongue is bigger than Dixies! He will give one kiss and stop. Ask Dix for a kiss and she licks your face off

Yuk!
I have heard that some dogs lick hands out of submission, my ex's jrt used to, if you stood near him he rolled over and if you bent down to him he licked you.
x