[Toadling]

Unfortunately, the only way to tell right now is to view the item in the inspector. However, I do know that the Omni Group is aware of this concern and they've told me they have a feature request logged for adding some kind of indicator in the main content area.

I recommend sending them a "vote" for this feature by going to Help -> Send Feedback in the OmniFocus menu bar. The more requests they get to add this, the more likely we'll see it in a near-future release.

-Dennis