Good dressage happens not because we hit ourselves over the head with some overly judgmental technique or by emotional whims. We can only achieved a level of goodness in our dressage with simple, gentle and precise actions. Skill arises through repetition, consistency, proper view, a kind attitude, intention, proper posture, and good surroundings.
To succeed with the horse is to nurture every part of the ground from which the horse grows. Care is first demonstrated by how we cultivate our own inner attitude and awareness. Only than can we properly relate to the horse.
The teacher can only help when the student is willing to look at their actions. This may seem obvious but it is actually an unusual situation. Most riders are not attentive to the reality of the situation. It is not that the student is defying the teacher but that the student is ignoring their own part in the horse/human situation.
We must learn to be aware not because it is good dressage, which it is, but ultimately because the horse pays very close attention to everything. There is no deceiving the horse in this, only our own self deception is really possible. This is a very human thing to do. Learn to find genuine dressage by grounding yourself properly. Those who can overcome their own self deception can achieve genuine dressage.