Because you re talking to him in the same tone that you normally use to praise him. He doesn t care what words you use it s your happy attitude that he s responding to. Dogs pay attention to your posture, too. Crouching to the dog s level invites them to come or play. Standing straight with your shoulders back is a more commanding posture and tells the dog you are someone to be respected.
Dogs become very confused when their owners words, expressions and tones don t match.
Since your signals are mixed, he can only guess at what you want or what will happen to him. To be most effective when training and communicating with your dog, your expression, eyes and tone of voice all must say the same thing. You need to use different expressions and tones for different situations and keep those signals consistent. When you tell your dog to do something, use a low-toned, firm, matter of fact voice. This is as clear to the dog as it gets he sees that you expect him to do as he s told and if he understands the command, he will do it.