Occasionally you get MP3s which have unconventional tags. I usually get this problem with compilation albums and it's a bit dull to rename them in iTunes.

There's a ruby gem which let's you easily edit id3 tags called 'mp3info'.

Here is a script to get you started:

require "mp3info"

dir = '/opt/music/album_name/'
Dir.entries(dir).each do |file|
   next if file !~ /.mp3$/ # skip files not ending with .mp3
   Mp3Info.open(dir + file) do |mp3|
      puts mp3.tag.title
      puts mp3.tag.artist
      puts mp3.tag.album
      puts mp3.tag.tracknum

      # You would perform your text transform here, here's a simple change instead
      mp3.tag.title = mp3.tag.title + ' with my change'
      mp3.tag.artist = mp3.tag.artist + ' with my change'
   end
end