I believe this also happens when the user has tracking turned off by various means in their browser.  I have the plugin that prevents me from being tracked by GA in Firefox and it was still registering download events (but not any events triggered via javascript).  So I'm not sure what an appropriate name would be.

CIDs are supplied by google, so I'm not sure what would happen if we started generating our own UUIDs from auth info.  The default I'm using here is an example copied from googles documentation, so I figure its not likely to overlap with a real person.  On the other hand the chances of uuids colliding is probably next to nothing.  So perhaps we could do this?