Unreliable Item Count in Search Scopes

Beware with the Item Count column present in Central Administration, in the Search Scope Properties and Rules interface, as it may not be accurate.

It does state it is "approximate", but what does it mean?

What happens is it queries the Search Service to get this Item Count, using the current logged on account (in Central Admin) which may or may not have permissions to see all the results. So the Item Count retrieved is actually the one pertaining the current logged user viewing this page, and not a global result.

This will be an issue in highly security trimmed contexts, where there is probably no account with access to the entire index (except for the crawler account). Therefore, the Item Count will be pretty much useless.

This design flaw in the Central Administration seems to be present since MOSS2007, as it can be seen here.