Amazon "kindly" suffixes ' [Explicit]' onto the track names of mp3s it sells where the album qualifies for parental advisory (as well as the album title itself).

I corrected this by adjusting the ID3v1 tag for each track. So far so simple, but the files have an ID3v2 tag too. I don't need both, so I thought I'd remove the ID3v2 tags:

ls -1 | xargs -n1 -d '\n' -P0 id3v2 -d

Unfortunately id3v2 seems to have an undocumented feature: when you strip the v2 tag, it copies the values across into corresponding v1 tags, thereby undoing my corrections.

Aside: I learnt about the -P argument for xargs from a thread regarding an ITP on debian-devel a month or two back. It's particularly useful for jobs like audio encoding.