How do you know one of the dogs won't lunge out at the dog you are walking and bite the other dog or the trainer?
They are calm, and calm on command is what we teach the dogs and what people really want the dogs to be, to just exist in the house and allow things to just happen like normal houses run and the dog to not react to everything that is going on.
We recognize the start of arousal and the start of the cycle of bad behavior that dogs have.