That has always seemed kind of inconsistent to me. Give a TSO a low-level clearance and he/she has virtually unfettered access to the secure areas. If the TSO does turn out to be untrustworthy, TSA points out (correctly) that previous behavior is no guarantee of future behavior.

Give someone else (military, government contractor, etc) a much higher clearance level and they aren't allowed the same privileges at the airport.

I don't believe there's something unique or different about the background check that a TSO gets that is specifically oriented towards ensuring that he/she is a died-in-the-wool trustworthy patriot.

I do know when we had clearances at work, they were regularly reviewed and 'updated' as necessary. Rare, but once in a while, someone's clearance didn't pass and was rescinded. (In one instance, we suspected the guy's bad divorce and subsequent heavy gambling and financial woes may have been the reason).

Do TSO clearances get routinely reviewed?