A reputation server is coupled to multiple clients via a network. A security module in each client monitors client encounters with entities such as files, programs, and websites, and then computes a hygiene score based on the monitoring. The hygiene scores are then provided to the reputation server, which computes reputation scores for the entities based on the clients' hygiene scores and the interactions between the clients and the entity. When a particular client encounters an entity, the security module obtains a reputation score for the entity from the reputation server. The reputation score may comprises a statistical measure based on a number of other trustworthy or “good hygiene” clients that have a hygiene score above a threshold. The client communicates this reputation score to a user with a message indicating that the reputation score is based on other clients deemed trustworthy.