Is it possible to use iTunes Match to replace my existing metadata with metadata from the iTunes Store? My music in my iTunes library has come from many sources over the years, and it's filled with incomplete or inaccurate or simply missing data, not to mention the fact that most of my stuff doesn't have album art associated with it.

I had hoped that as part of the 256kbps 'upgrade' functionality that iTunes would also upgrade the metadata on my songs to the metadata that they ship with the iTunes Store purchases. However, deleting and redownloading a matched song only upgrades the audio data, but keeps the metadata intact. Is there a way to upgrade the metadata as well?
No - the design clearly is intended to honor whatever set of metadata you have currently entered into your library. As you have discovered, the matching process can find songs based on other criteria and re-downloading the "canonical" AAC 256 kbps stereo will not currently fill in any metadata holes or correct parts of the metadata that do not match what Apple has in the store (or it's Match database for songs that are not for sale like the AC/DC catalog)

I can see two reasons for this:


Intentional - preserve user customization where the data may be better on the individual customer iTunes database.
Not automating the process of cleaning up songs that may have been passed or downloaded rather than ripped when connected to a metadata lookup server or otherwise encoded by the official artist when it was sold or released.


I specifically have hundreds of Hawaiian songs where I've entered the metadata with the help of a native speaker to have the correct punctuation (and that doesn't match Apple's punctuation). There certainly is a great need for a tool to help people manage this, but iTunes Match isn't that tool today.