They offer the dog some privacy and place to rest. Dogs can be taught to respond to anything. Normally spoken words or used and traditionally those are in German. We do know these few things about them however. A large breed dog has 200 million olfactory cells compared to a human's 5 million.
Dogs have as much exposed area inside their nose as they have on their entire body.
Finally, there is a bulb in the roof of their mouth, just behind the front teeth called the vomeronasal organ. It is directly connected to the olfactory lobe of the brain by nerves. When a dog licks the tongue passes over this bulb for instantaneous odor sampling. Imagine a 100-yard dash in 7.14 seconds. Dogs are extremely smart.