Originally Posted by Feralpudel

From my own experience, obsessing about equipment doesn't get at what makes a dog a happy worker or a confused, worried, shut-down (non)worker. I've used a prong carefully on two high-drive poodles and never seen resentment or fear of the collar. On the other hand, I've managed to shut down a non-poodle without touching her, with a handful of food and a clicker! Why? Because she still felt the pressure of my expectations and didn't like it. And the only time I have upset Dexter in training, he was off-lead doing a recall, and sensed my frustration when he was distracted by a puppy behind me.

In my experience, lack of clarity and negative emotions are what really upset a dog.