The document discusses some of the hidden dangers of using Facebook based on an expert's analysis. It outlines 5 main risks: 1) personal information being shared with third parties through applications and connections; 2) privacy settings reverting to less safe defaults with site redesigns; 3) ads potentially containing malware; 4) friends unintentionally exposing personal information; and 5) profile information retention even after deleting accounts. The expert warns that Facebook's business practices sometimes compromise users' privacy for marketing goals.