BTW -true story from about 15 years ago and I think it is relevant.
My brother (always amused by human anatomy below the waist) was having a pint with my father in The Dungeon Ghyll in The Lake District UK. He was amused by two dogs and of course one dog started licking and sniffing the arse/... of another dog. Well my brother turns to my father and says "Watch this, I bet you a pint of beer that within the next minute or two that dog will now go and lick the face of its owner". Sure enough - exactly what happened.
I say this because although I like dogs, I would not want one licking me - sniffing OK.
EDIT - glad the British English Slang for the buttocks etc does not get auto-edited out.