Joel is trying to figure out if he should support custom fields in his bug tracking software. He gives some good reasons why not to, specifically if it intimidates or makes it more cumbersome to file a bug, then it probably a bad thing. This advice should be in bold letters in the help, or the ui for adding custom fields. There are times when a custom field doesnt affect the file-ability of a bug. An example is something automated in the source management process. When windows went from a single tree, to a branch/main build system, our bug tracking software needed to carry an extra field to tell us not only what branch build a bug got checked into, but also what main build it was reverse integrated into. This was a field maintained by our build/integration process, and remains extremely valuable.