Adding clone to Spotlight Privacy only works a root
 

I have used SuperDuper to clone to an external USB drive, after a successful clone I tried adding that drive to the Privacy pane of Spotlight and it would not work as a standard user, it would not work as an admin user, only root could add the drive. Is there a reason why please?

It sounds like it might be something in Spotlight's implementation, James.

Just another one of life's little mysteries :).

There are definitely black boxes involved in some of this stuff!