Bubba, the black lab has strict requirements for approaching people.
If they are walking toward him, they want to pet him.
If they are walking away from him, they want to pet him, but have somehow gotten turned around.
If they smile at him, they want to pet him.
If they cringe away, they want to pet him, but are just shy.
As a man we met remarked, "That's a big dog, but he has a puppy brain."
Shelley won't approach someone until they look at her - but once they do, they better brace themselves . . . she never met a stranger.