This document discusses consistency as a service (CaaS) for auditing cloud consistency. The CaaS model consists of a large data cloud maintained by a cloud service provider and multiple small audit clouds consisting of user groups. The audit clouds can verify the consistency level promised by the data cloud's service level agreement. A two-level auditing architecture with loosely synchronized clocks allows the audit clouds to quantify consistency violations and devise strategies to reveal many violations. Extensive experiments validated the heuristic auditing strategy.