I can understand the motivation for wanting to handle
ID3 tags in FLACs since some broken programs are
writing them, but it would be nice if the "flac"
program told people when it was skipping ID3 tags, and
that they were out of spec. We recently got a bug
where the user was confused because "flac -t" had no
problem with the file, but it had an ID3 tag, so it
looked like our tagger was buggy. For -t, I think it
would even be appropriate to fail if it encounters an
ID3 tag, since all it's supposed to do is test validity.