One other thing we should always bear in mind is that any behavior can be enhanced learning. Psychologist BF Skinner immortalized the concept that reward increases the likelihood of a response. So it is with licking. If a dog licks his owner’s face — perhaps as a vestige of maternal lip licking, perhaps out of anxiety, or just because his owner’s face tastes salty — and his behavior is greeted with attention, hugs and (human) kisses, he will likely repeat the behavior in future. In such cases the dog learns just how to push he owners buttons and the owner becomes analogous to a vending machine.
Do dogs lick to show love? While face licking may not represent true romantic love, it nevertheless can sometimes be interpreted as some token of a dog’s affection or respect … and that’s nothing to sniff at.