In "Public records outrage of the day: North Providence edition", WPRI (Providence, Rhode Island, Channel 12) shows two copies of a police report: one with everything redacted, and the second provided after a verbal appeal (which amounted to asking "Is this a joke?"). Here's the first one, in which nearly the entirety of a police report has been blacked out.
There are plenty of reasons to appeal a rejected FOIA request, and overly zealous redaction is high on the list. If the document has been obliterated by redactions, you should always appeal. The Sharpie wielded by the first person to do a hasty job on marking out information might well be different from the careful editing done by the next person down the line. You can strenghten your argument by asking the agency to be specific about which exemptions from disclosure it is using, and asking that exempt material be separated from non-exempt materials.