Here's cover art / on the other hand, here isn't!

Question

I initially imported a handful of my albums to iTunes (henceforth referred to as *"initial albums"*), used the function to d/l cover art for them, which turned out ok. Later I removed this library, started a fresh one and added all my music, applying the cover art function. This time, however, iTunes failed to retrieve album covers for several of my "initial albums" (for instance incl. four albums by the same artist).
These initial albums are common pieces of music that are all available through the iTunes store, and at least some of which you expect to find on the shelf if you pay your local record store a visit. I should point out that in between these to library builds I did edit some of the tracks' tag information (although only minor alterations like adding year of release, comments, etc. were made).
Kudos to the one who coughs up an answer to this one!

Answer 1

My experience is that for automatic artwork look up, the two pieces of info that must match exactly are Artist name and Album name. If you changed any of those two, that might be the issue.
And it can be somewhat subtle. For example, I couldn't figure out why a "Mighty Mighty Bosstones" album wouldn't get the artwork when I could see the album in the store. Turns out that I was missing the leading "The" from the group name. Adding that in to create "The Mighty Mighty Bosstones" solved that one.
Other times I have found very slight differences in album titles especially with punctuation and articles (the, and, etc.). For example, AND vs. &, or titles like (just making up a title off the top of my head) "Joe Blow Greatest Hits" vs. "Joe Blow - Greatest Hits" (Note the added DASH in there).
I have found that if I go to the store, highlight the line of one of the songs on the album, do a COPY then open Text Edit, Notepad, etc. and paste it will paste in the entire line of info (it doesn't seem to allow you to just highlight and copy the artist or title), then highlight the artist name or album title, again do a COPY, then go back to iTunes, select the album, Get Info and paste in the version you just copied which WILL match iTunes version.
Best of luck,
Patrick