Scams, policy abuse, and friendly fraud create nightmares for e-commerce and retail merchants; online marketplace, gambling, and gaming merchants; and dating site operators. These fraud types refer to fraudulent, disruptive, or harmful behaviors of hitherto good customers and pose financial fraud loss and reputation risk to merchants. This report highlights the most common modalities and channels of scams, policy abuse, and friendly fraud and offers process and technology best practices for their detection and mitigation.