I've been told that they get grouchy when they are shedding, but I have been lucky personally that none of the ones I have interacted with are grumpy when they are shedding. My dragon is pretty relaxed most of the time, so even if he is shedding he is pretty calm. I do make sure he gets his
bath every day though when he is shedding, it gets all the skin off alot easier and it makes him more comfortable.
The ones at the store we usually get at about 2 months old, so pretty young. The first few weeks after they arrive, they can be a bit fiesty, but I have never had one bite me. They usually either run or stand their ground and puff up their cute little beards. But usually they keep their mouths closed when they do it, so I just reach in and rub their beard and talk to them a bit, usually "Hey Mr.Man who do you think you are? you think your bigger then me?" Just remind yourself that they are babies and your gigantic and even if they do take a snap at you, it won't hurt that much. I've noticed that when I coach other employees on how to handle them, that if one puffs and they pull their hand back that beardie will puff more often. I think the people here are correct that they are not dumb and if they see you retreat when they puff they will think they have the upper hand. In the wild, when they puff up and another dragon retreats, they think they're tuff stuff. You just can't give in to that. Otherwise they learn that they can get away with it.
If a puppy bites you, and you give in to that, he will grow up to learn that biting gets him what he wants.
Same sort of idea with these guys. If your really afraid, wait until the morning before he has his lights on and try and hold him then, or at night time. Those times they are sleepy and slow, they are the most docile then.
Just have confidence in yourself and remember that you are getting to know each other and your much bigger then him, I think you'd have the upper hand in a fight and I think he knows that too.