Ultimately, it is the dealer's decision but I think Neil has the right idea. Who in their right mind would take paypal from a first time buyer for the sale of an illegal item?
As for the noobs who find the dealers through the forums I have no sympathy. Why? The neophytes wouldn't know about the dealer otherwise. If a noob doesn't trust the reviews by other members than we don't want them here anyhow. Finally, if there is a problem they should be bright enough to know they can publicly raise it on the forum.
At the end of the day I don't think there is a way to police the membership effectively. The dealers have to make their own decisions and they should certainly have access to a bad buyers list either on the forum or amongst themselves.