Often when our dogs come in they have been off eating manure from various species; their tongues are green or brown and it is still stuck on their teeth. Allowing them to lick me would similar to smearing manure on me.
A couple of our dogs will periodically clean out their anal glands with their tongues.
Our guardian dog, Sam, has been enjoying consuming the after birth left by our ewes.
A couple of our dogs like to clean off the bottoms of our boots after we've come in from the barn and barnyard and taken them off in the mudroom.
We do not allow them to lick us.