system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Are dogs actually happy when they are smiling or do we just think so because we perceive a smile as positive?

and no I do not mean when a dog just shows its teeth, I am aware that is just aggression.
gpt
Some dogs do actually smile, as we do, but it can also often times be a sign of stress or a need to cool the body by taking in and letting out large amounts of air. Dogs are much better at reading the subtle differences, than humans.