every state is different, but if you are legal in your own state and carry a copy of the statutes with you, you should be able to argue your way out of a ticket or confiscation. and you should also be able to show that you are from that state as well, not just trying to have a moped from an unregistered state.
doesnt mean you will not meet a cop who will take an opposing view, but be polite and stick to your states laws.