So my MP3 library's been a mess for a long time. I have a large folder full of MP3's called "Bad Tags". They're the tracks I don't listen to very often and have tags that are messed up. In most cases I'm too lazy to get the CD out of the attic and re-rip it and it would take forever to re-type them. My most common tag issue is truncated fields or the infamous "Track 01" song name from back in the days of using Real Jukebox. Man, those were the days. Then Sound Jam on the Mac. Nostalgia! Anyway, lots of bad albums.
Enter Music Brainz Picard. It makes cleaning them up a breeze! If you have MP3 tags that are wrong and want an easy tool to clean them up in, Music Brainz is the best free tool I've ever used. I've used some of the 'fee' based ones. They're good and all, but I don't like to pay for a tool I'm going to use once and never again. It's back-ended by the MusicBrainz meta data database and it quite extensive.