Sometimes using a noise aversive (like a penny can), can backfire and make a puppy frightened of anything resembling a can. Using something like a penny can or a spray bottle also relies on us having those items the exact second we want to interupt our puppies. An 'interupter' that is always available is our voice. If we use a verbal reprimand like "No." or "ah, ah!" we must realize that it's JUST an interupter. It doesn't really install any kind of knowledge in our puppies. They don't really know what "no!" means. Anymore than we would know what "Blah, blah, blah!" means if someone came up to us and yelled that. We would probably stop what we were doing at the moment. But we have no idea what that means. It would work to 'interupt' behavior. The best thing we can do when using an 'interupter' is to then redirect our puppies. Think... interupt, redirect, reward. or... interupt and time-out.
It's nearly impossible to train the 'absence' of a behavior. Especially one that our puppies are so hard-wired to do. Biting is so natural for them. Whenever there's a behavior that I want to get rid of, (like play-biting), I don't focus on "how do I punish this behavior", but rather... what would I rather have my puppy do right now. I'll help my puppy do THAT behavior and make it very rewarding for him so he wants to repeat it. So maybe my boxer likes to attack my ankles or hands. It's my job to think of a 'game' he can play that will help get rid of his pent up energy, and that doesn't entail putting his mouth on me. Like, attack the squeeky squirrel. Or fetch the ball. or play a structured game of tug or war. Any time he makes a mistake and does something I deem unacceptable (bite my clothes, or skin, claw at me, jump on me.. etc... ) I will immediately END the game. period. His behavior... biting my hand for example, caused an immediate consequence... END of FUN. In essence we're saying, "guess what puppy... you bite me, you play ALONE". And because WE are the reward when our puppies are play biting us, the removal of that reward is a clear and meaningful consequence.
I encorporate lots of fun games in our training. And some even get my puppy riled up... but it's an awsome way to teach our puppies the rules of engagement. If you want to play with people... you MUST keep your teeth OFF. Boy if your puppy loves his training games, they very quickly learn the rules.
Also, we really have to admit to ourselves that if we do have to 'punish' our dogs for breaking 'our' rules, it's really just an admission by us that we have not yet trained the puppy. They don't come knowing the rules. Nor do they understand that virtually all naturally dog behavior is unaccepteble to us! Poor pups. It's really hard for them!