These dogs have learned that behaviors their owners really don't like (slobbering on clothes) will always get their owner's attention where other behaviors they have tested were ignored by their owners.
Is this the sign of a dumb dog?
LOL! Let me give you my primary example. Jake does all basic obedience, hugs on command, stays by my side when walking (even on the beach), knows which door to go to when I say "X" is home (hubby comes in through garage, son via front door), and is otherwise very responsive to all commands. Except "paw". He WILL NOT give his paw. He will tap you on the shoulder with his paw if HE wants a hug, but if you do the standard command he looks at you with this blank look and won't lift his paw. Ever. We withhold any reward if he doesn't respond so we aren't rewarding bad behavior. Maybe in his mind he feels he "wins" on this one!