It's usually pretty clear that dogs lick because they like people; it's their way of being affectionate. There are other reasons dogs lick, though, such as prior to feeding from their mom, asking for a dinner invitation, exploring something, attempting to get attention, or even a way of playing.
Dogs may also lick because they think you taste good! Your taste and scent is familiar to them, and then if you pet them after they lick you, they are rewarded for it. However, you should always pay attention if your dog is licking him or herself. This could signify a medical issue such as anxiety, obsessive-compulsive disorder, or even allergies.
According to petmd.com, licking due to anxiety is similar to nervous habits that humans have such a biting fingernails or drumming one’s fingers. They interviewed some behavioral specialists in order to get a better idea about dogs’ nervous licking.
Dr. Megan Maxwell explains that it can be nervous licking depending on what and when a dog licks, such as if your dog always licks something when the doorbell rings or if they consistently lick the same thing over and over again.
Regardless of the reason for licking, you might want to keep a towel handy to wipe up all that slobber.
And no matter how much you love your dog, we don’t recommend licking him or her back.