I doubt that, at least in the literal sense of smelling. Dogs can however distinguish behavior patterns in their handlers, because that's mainly how they get r

I doubt that, at least in the literal sense of smelling. Dogs can however distinguish behavior patterns in their handlers, because that's mainly how they get rewards and are punished. Both the patterns and the rewards are much more subtle than handlers are generally aware of. A service dog is in some sense the worst case of an overfitting machine learning model you can imagine.