Anyone who doesn’t seem to care if their horse is, or might be, in pain. Had an instructor INSIST on working a lame horse (claimed the horse was “just lazy” and needed to be forced to work harder to fix her attitude) barn manager ended up putting a literal lock on the stall door to stop instructor from sneaking the horse out. Turned out horse had suspensory injury. Instructor still works there, never did apologize or admit to her wrongs. Needless to say I left that barn, and that instructor.
People who don’t do their own work with the horse (mucking, feeding, turnout, etc.). I don’t mean the people who don’t have time, I mean the ones who have the time but refuse/dread doing it. I would have killed just for the chance to muck stalls when I was younger, and even now my favorite part of the day is morning feed. I’m in the sport for the love of the horse. The horse isn’t just an accessory piece to success.
People who think they know more about your own horse than you do. Brought in a trainer to work with my OTTB while I was injured. After 4 rides she insisted she knew him better than me, had him doing questionable things after I told her he was still recovering from a soft-tissue injury and needed to work up to full-work slowly, and ended up turning him into a bucking bronco and then refused to get him on again (and somehow managed to tell me that it was my fault???). She then told me he was never going to get better. Little did she know, the weekend after I fired her I rode him, did the “difficult” transition perfectly, no bucking or antics, quiet as a lamb…some people, man.