There is a service that warns merchants of fraud-likely customers. Precharge. I was surprised to not see it anywhere on HN to date.

You can learn more at http://precharge.com/guaranteed_chargeback_protection/

Essentially you pay Precharge to qualify the customer and if it passes their fraud checks, they will reimburse or fight the chargeback.

They might be maintaining their own repository of problem customers here: http://www.chargebackfile.com/

Hope this is helpful to anyone considering mitigating chargeback risk.