1. A method of providing computer security, comprising: determining client hygiene scores associated with a plurality of clients that represent assessments of abilities of the clients in avoiding malware threats, the hygiene scores based on amounts of malware detected at the clients; receiving data describing an entity encountered by one or more clients of the plurality of clients; and calculating a reputation score for the entity responsive to the client hygiene scores of the one or more clients of the plurality of clients that encountered the entity, the reputation score representing an assessment of whether the entity is malicious.