AppleScript is great for performing tasks that can be aggravatingly repetitive for humans (Mac-using humans, anyway). However, it is not always the best solution to a perceived problem with tag editing in iTunes.
It seems to me that some users are ignoring (or are perhaps anxious about using) several built-in features of iTunes that makes tag editing relatively fast and simple.
Doug Adams, the guy who writes AppleScripts for iTunes, points out some of the features in iTunes that let you edit tags efficiently without needing AppleScripts. You shouldn’t start looking for scripts to tag files in iTunes until you know all this stuff.