The trainer seemed stuck in one type of training. Closed minds seem to run a potential client away fast. Customers appreciate a trainer who tailors himself to the dog, not vice versa. If you recently left a trainer, after establishing a relationship, tell us why. Obviously, there is some overlap here.
People leave for the same reasons they gave above.
Most come down to respect issues. Ouch, those are strong words. If money is your only motivation for training, it shows. To be a great trainer, many believe that you must first relate well to the people, not just their dogs. Plus, every person is different.