Absolutely! Ever see a dog that knows how to "smile", some mistaking it for a snarl when they first meet the dog? This is a learned response. I've had many boarders in kennel that know how to smile. It's fun to greet them in the morning. I've found, over the years, that the herding breeds are best at this. A big smile/snear, upon excitedly greeting someone and then bowing their heads or dropping a shoulder sideways and wiggling up to you for contact. I believe an owners smile, laughter or exhuberant greeting is what cues most of these dogs.