Here is in lies the issue..
Meta Tagging of files is a good thing, but you should also have policies that are looking for the actual content that is most important to the customer (SSN's, PCI, and Keywords)
So they should have a couple of policies, one that looks for the content alone, MetaData & the content, in addition to just the MetaData.
You need to have policies that cover the gambit of ways to detect information, not just one
Ronak