Reports: If NULL return empty value

I'm working on creating a report and have noticed some fields that are empty in CRMoD but show up as "Unspeicified" or "-27" entries on a report. I'd like for empty results to show up as blank cells. I'm thinking I can resolve this by going to "Edit Column Format > Data format > Override Default Data Format" and entering a string into the Custom Text Format selection. Am I on the right track? Any suggestions would be greatly appreciated.

-rs