I think it is funny that these threads really just end up being most people listing their favorite albums and not perfect albums. Perfect albums are very rare and some years I do not think that any are even released.
For an album to be perfect it does not even mean that I have to love it. For instance I feel that Miles Davis Kind of Blue is a perfect album but it is not one of my favorite albums of all time. I do not listen to it regularly but I can appreciate how flawless and complete it is from the first note to the last. There is not a moment on the album that could be done any better than it already is.
One band that has been mentioned numerous times in this thread is Tool. I do not see how a band like Tool could ever put out a perfect album. Their albums have too much filler be it just noise or some guy speaking at me in German. It is interesting the first time you hear it but I guarantee it is skipped almost every time thereafter.
I think that there's something in this, but when I posted my feeling was that "perfect album" means an album that works as a total experience, not simply a collection of ten or twelve great songs, but that you really need to listen to from track one and keep going to the end.