The properly trained dog is typically quite proud and likes to show off his achievements. Without a doubt a reputable and well trained dog will always be far more content and happier than his untrained counterpart. He has his jobs and responsibilities that allow him to secure his place within everyone.
If canine can understand these basic commands, its easy for the dog to understand the instructions when you are looking at be trained to perform a feat for jumping through obstacles.
You see, when a Dog brain training growls, you at least know the dog is giving you a alert. Now you can try to understand why the dog is growling and do something to fix the aggression problem.
The best advice, see a dogs- or otherwise the dog behavior tools agility forums online. As you well know it