Thanks to Malady for a genuinly interesting question. I was speaking with a friend of mine about this exact problem, and we came to the conclusion that it is all relative.
I don't mean to be big headed about the subject, but most people don't have the experience of so many dogs, nor the interest of studying them (I have to admit it is a geeky subject that I am in love with ) So I am suggesting that COMPARING dogs to dogs gives you a good grounding to then state 'this dog is healthy'.

Today I met a 5 month old lab puppy that I immediatly guessed was fed on one of what I consider (based on my findings) to be a 'lesser' dog food. The first thing that came to mind was his drab coat, and I guessed the food straight off.
Going to shows, and being out and about, I have actually guessed which dogs were fed on a 'natural' diet, something I am slightly concerned about. (Esp. over the age of 2) If there is a difference that is obvious to me, why are not more vets picking this up. (Or perhaps that is a question that has an answer I will be frightened to hear)

p.s. the friend I was speaking to has a poodle with the long hair, who positively shines. He has been fed a natural diet from day 1 and is approaching 3

This calming signal can be a good sign.

As you both put, can If a dog is calming, i would say its calming for a reason as a dog who is already calm would have not reason to calm, these reasons can be a number of things including illness that may not have a major visiable sign.

The same with yawning, it is a way to charge themselves up and calm themselves down.

The point being made was that yawning/lip licking is not necessarily a sign of illness as you stated. It can similarly be a sign of excitement and renewed energy, which some could mistake for being ill.

Do you get blood work done Malady? I was thinking about it....