If we let people get away with producing bad XML, then we're heading down a path that leads to the same sort of nightmare that we currently have with HTML.

Agreed. Perhaps a suitable compromise might be to attempt to identify badly formed RSS using your Good XML/Bad XML test and alert users if a site isn't outputting information properly and why this is bad. Maybe using <BLINK> tags. ;-)

At present, my application only runs on the intranet where I work, so advocacy of well-formed XML isn't such an issue.

Anyway, I'm off to perform another violation of my beliefs and print out documentation to MS-Word. It's not for me, though. Honest!