Physical Touch and verbal affection can be extremely valuable or extremely hurtful
The reason why we do not pet our dogs all the time is because we want our physical touch to be valuable. We want the dog to differentiate what we like and what we don't like and we want the dog to know when he has done a good job. For example, if we ask our dogs to 'sit' and they comply, we mark it with a verbal 'good' or 'yes' and then give the dog a small pet on the head to reinforce. If you pet the dog too much, you will just get the dog amped up and he will quickly go from calm to excitable in seconds. Another reason why we don't shower the dog with affection, is because when we pet the dog, our demeanor automatically softens, and dogs go by our energy. If they feel that you share a soft source of energy, to them, it means you cannot protect them and their instinct is to take over the pack. Affection can hurt your dog if you aren't giving it at the right time. Also, we don't talk to our dogs. The #1 reason is because they are dogs, they don't understand what we are saying unless we teach them what the word actually means. Always ask yourself- Are you petting a dog in a calm state of mind or are you petting a worried, stressed, nervous, insecure dog? When you say "no" to your dog, ask yourself- Have you taught your dog a valuable meaning of the word 'no'?
Do you know what you are reinforcing? Think about that.