For most of us, a horse that rears, bucks, bolts, bites, or kicks  is a dangerous horse. What may seem cute or exciting to you, may not be for someone else. Everything you teach your horse or do not teach your horse will be part of him for the rest of his life and although we say we will keep them forever, you can not guarantee this for your horse. If not for your safety, then for the horse's safety and the people he may be with if you ever have to let your him go, teach them manners, only accept good behavior and never teach them to rear or kick out as a trick. 

Please see links for training articles below about respect and horse behavior.