The reason why banks refuse some categories is almost always that they've seen high rates of fraud, chargebacks, or money laundering in those categories.<p>The auction category sees high fraud rates, because it's easy for crooks to set up fake merchants to launder money from stolen credit card numbers. They also see high chargeback rates, because there will be people selling crap. Also, they get in trouble with federal regulators if they facilitate drugs or weapons purchases.<p>eBay is the way it is (high fees, strict rules for sellers) largely because of these forces.