I have a friend with wonderfully mannered QH's. One of her horses is very bright and yet very lazy. From the first time I trimmed him, if he so much as leaned a bit on me, the owner quietly asked me to step out of the way and then proceeded to make the horse turn his hips. This was done with a halter and rope, nothing more. This horse is a dream to work on.
Nobody ever loses their temper.
People often think they need a trainer or a round pen or special equipment or a farrier who doesn't mind carrying their horse on their back. Really, all they need is to be consistently expecting manners from their horse and a few simple ideas on how to get them. I really don't care if the horse stands like a statue for the owner to pick out the feet. I care that he is trying to turn me into a pancake under him when I'm there.