One of reasons I strongly encourage horse owners to train their own horses rather than ship them away to a professional trainer is familiarity. Quite simply, an unfamiliar party will not understand your horse nearly as well as you, and this understanding of a horse is backbone of any successful training plan.
This is not to suggest that all horse trainers are clueless individuals that bumble along hoping to do something right, because most professional trainers will take time to understand a horse before ever thinking about saddling him and training him to ride. But all too often an impatient or inexperienced "trainer" will misread a horse's problem or intention and react incorrectly due to his lack of understanding. Too many of these incidents can prolong training process (thereby costing you money) and potentially mentally scar your horse for life.
Far too many head-shy horses can be attributed to inexperienced or abusive past trainers and/or owners who lacked an understanding of horse they were working with. Once a horse has developed this mistrust or fear of people it can take a good while to reassure horse that another cuff is not waiting around corner. And who can blame horse? If every past exposure with a dog resulted in dog biting you, chances are you would be very wary, if not outright panicked, by future exposures to canines.
To correct an improper action it is first important to understand motivation that lies behind it. For example, let's say that you are training a young filly to walk alongside you to your left. Suddenly without permission filly slams against your side, but being that she's still young it doesn't do much more than get your attention. What would you do?
1. Ignore behavior – no harm was done after all.
2. Jab your elbow into filly's shoulder and growl at her to remind her to respect your space.
3. Take a moment to detect reason why filly brushed against you.
If you selected first option, you chose wrong. Although your heart is in right place in your willingness to "write off" a seemingly harmless action, eventually if you ignore these things they can compound to worse problems. Your filly won't always be so small and light!