Ubuntu: LTS to LTS+1 upgrade leaves cruft

Over the past few weeks, I upgraded my Ubuntu hosts to the Precise release due to be published next month. While the upgrade on my desktops from Oneiric to Precise went mostly well, the upgrade of my terminal server from Lucid to Precise was more daunting. In short: too many packages leave an undue amount of cruft behind, namely tons of obsolete configuration files that are not correctly handled by maintainer scripts, to either delete obsolete files or to rename them to the currently valid filename. At Debian, these oversights are periodically monitored using piuparts and reported to the package maintainer, but Ubuntu doesn't seem to offer this sort of automated Quality Assurance process yet. Perhaps this would be something worth developing?

PS: For those who wonder how I spotted those obsolete configuration files, I simply enabled the FLAUSCH environment variable before running upgrade-system.