One of the more interesting aspects about agency processing of FOIA requests is how inconsistently they apply their own internal standards.
For example, during the past 4 or 5 years, the FBI has offered requesters the option of receiving files on CD’s instead of just as paper photocopies. As a result, I have requested files which I originally received 15–25 years ago as paper documents. What I discovered, is that the newly released files (on CD) are often much more heavily redacted than the exact same files which I originally received decades ago as paper documents.
Furthermore, the FBI redacts information which is already in the public domain — such as names of corporate officers appearing in corporate articles of incorporation and names appearing in press releases and newsletters of organizations which intended for those names to be made public as a means of showing the stature of their members and endorsers.