I know you run your new albums through Picard, but have you done “regression tagging”? I’ve been spending a little time retagging my massive music library in groups of letters. Most of it is already tagged, so Picard picks up it quickly and i notice that 50% have modifications (e.g. updated year, misspellings, etc)

Also, I did the unthinkable: I cleared all album artwork. That’s right, I selected all 45,000 songs and checked the artwork field with nothing in it and clicked save. It took a few hours to remove them all. I think there were some problems because Picard has an option to embed the artwork in tags (?) I don’t like the sound of it and i think iTunes didn’t like it either.

One other good thing about regression tagging is that I was able to find broken/incomplete albums. Not that I am planning on completing them, but it’s definitely an easy way to find that stuff out.