It happens more than often that at shows you see trainers yelling at the sideline, giving last "instructions" to their students before they enter the ring. It makes you wonder whether the decibels, produced by the teacher's non-sensical oral noise, are going to equal the marks on the student's score sheet after the test?!
You have these teachers which believe that by becoming dominant over a student, the process of learning is fuelled. Their knowledge about training is irrefutable and the only thing the rider has to do is "shut up and ride." Not everyone agrees with this system of training. Some students like to express what they feel, when they are in the saddle, and are not at all reluctant to give their own opinion, sometimes in a blunt way. Other students have the guts to question the trainer's system as they believe that they know it better. The result is that they get reproached by the trainer, which makes the client leave the barn and spread bad words about the former stable s/he boarded at. Gossip is a powerful tool.
It is supposed that the trainer knows "the system" well enough, but is he also able to get his message across? You often see excellent dressage riders who completely lack the ability of passing on knowledge. Their instructive skills are nihil and it all comes to the end that his name is able to lure many clients, but that the students hardly learn to ride.
Than you have that sort of trainer which has a barn full of clients but still makes so many mistakes himself (proof lies in the trainer's own show records). His own mistakes are passed on the students who will be unable to produce results at shows. Parents get upset for spending large amounts of money for quality tutoring and students crack mentally. It is the trainer who made his name at competitions, while the students fail to break through.
Great trainer legends claim that training and showing are two different things and that a career in both disciplines is impossible. You either are a competition rider or you coach. A picture of the ultimate trainer could be, for instance: a horse lover who knows what he's doing, who is possibly being instructed at the same time, who takes the time to go to shows with his students, and doesn't run around the grounds in a hurry as he has to get back in the saddle himself. The ultimate trainer is someone who is able to earn the student's respect (and his keeping quiet in a lesson) through his knowledge and humaneness. Am I rambling?