How can I prevent our dog from licking people? We just got him last year. Tank is a Border Collie. My sister-in-law passed away and no one wanted him. He is such a sweet good dog, about nine years old. He wasn't a house dog until we took him in.
You could exercise him more, especially if he's one of those working breeds, like German shepherd or collie. That would displace a lot of anxiety. To train him out of it, I suggest you firmly but gently snap him out of it, by either saying NO or otherwise starting him.
First, don't let him get in your face. As he is coming into your face, say, Sit! If he has not been taught to sit, start this right away. Also, don't let him jump up on people. Use the Sit! command for this as well.
(Note: Don't pull away or walk backwards. Stand firm and use the sit command.)
If he is licking hands: Yelp in a high pitched voice- "Ouch!"- when he does this. Don't pull your hand away. Let him stop and look up. Then give Lie Down command, which you will have to teach.
This is obsessive behavior. There are medications for this, or you can use massage or swimming for the dog to reduce anxiety.