If you train your slave properly, you can expect to see this kind of pride on it's face after an intense session of abuse because it's position in life is so thoroughly reinforced that it finds it's purpose in serving and accepting daily punishment.
I tied and left my wife in this position for my bully and his mates to use her however they please for a week.. I went downstairs to sleep in my guest bedroom while hearing my bully’s laughter as my wife squealed in ecstasy like a common whore..