How to tell if the Web Acceleration Profile cache has been cleared?

Just in case anyone else is wondering about this all of the cache info accessible from the API I found, cannot be used to completely confirm that a cache has been cleared. (mainly because the cache will still be in use) So I went with the simply trust it worked if it didn't error option as opposed to adding a race condition to the confirmation message (I take it this is why there is no response from the call)