Dogs use scent more then humans. However they still use sight and sound much morfe then they use scent.

Dogs use body language and vocalization to communicate with each other. Watch two dogs interact they look at each other and will growl, and bristle or tail wag and play bow to indicate what they want.

They look at faces on humans because that's a major component of how we communicate.

Smell is not how they communicate. It's just how they know where other animals have been.