What is the Opposite of a Diamond in the Rough?

We got into a discussion the other day somewhere in the comments on Gheorghe:TheBlog about the worst songs on the best albums, and this topic moved me so much that I decided to take action: on my Google Play Music account, I gave a thumbs up to every song on Led Zeppelin's Physical Graffiti except for one . . . "Kashmir" received a big thumbs down . . . and then I went through the Dire Straits album Making Movies and gave all the tracks a thumbs up except for "Les Boys," which I gave a decisive thumbs down; I'm not sure how this will affect my suggestions algorithm, but it made me very happy to express my opinion in this manner (although if you play the album, the song with the thumbs down is still played-- to construct the album without the "thumbs down" song, I guess I'd have to make a playlist . . . and I might start doing this-- removing a song or two from albums that I think are otherwise perfect and keeping the "Dave" version in my playlists, we've got all this wonderful digital technology, I might as well use it).