Whilst convincing dragons that I let escape I have observed that over the years my configuration database has acquired various unused and/or incorrect entries. For various reasons as the system has been upgraded entries have been made redundant and/or had their names changed as packages have been updated. Comparing fresh database entries to the older imported database shows new entries that aren't present in the older database or what seems like name changes.
As an example my qpsmtpd database entry had entries for qmail-amavis and spamassassin is now VirusScan etc.
I don't know if there is any automated way of cleansing the database (apart from starting with a clean config and not importing previous config databases ).
I don't know if its feasible to have some sort of comparison script that compares a database entry to the associated templates, of if it anything to worry about.