A fraud detection system may obtain a number of known fraudulent end-user profiles and/or otherwise undesirable end-user profiles. Using statistical analysis techniques that include clustering the end-user profiles by attributes and attribute values and/or combinations of attributes and attribute values, the fraud detection system identifies on a continuous, periodic, or aperiodic basis those attribute values and/or attribute value combinations that appear in fraudulent or otherwise undesirable end-user profiles. Using this data, the fraud detection system generates one or more queries to identify those end-user profiles having attribute values or combinations of attribute values that likely indicate a fraudulent or otherwise undesirable end-user profile. The fraud detection system can run these queries against incoming registrations to identify and screen fraudulent end-user profiles from entering the system and can also run these queries against stored end-user profile databases to identify and remove fraudulent or otherwise undesirable end-user profiles from the end-user database.