Dogs don't feel threatened by your intelligence. You can train a dog. Dogs are easy to buy for. You are never suspicious of your dog's dreams. The worst social disease you can get from dogs is fleas.
Dogs understand what no means.
Dogs understand if some of their friends cannot come inside. Middle-aged dogs don't feel the need to abandon you for a younger owner. Dogs admit it when they're lost. Dogs aren't threatened if you earn more than they do. Dogs mean it when they kiss you.