1. A method of detecting a cache condition, comprising: at a client: requesting a document from a location; receiving a first response from the location, the first response including a first value; re-requesting the document from the location; receiving a second response, the second response including a second value; and indicating the cache condition to a user when the first value and the second value differ; wherein the first value and second value differ when the second response is not received from a cache of the client.