Albums are rated by averaging song ratings with some leeway. Just my opinion based on my personal listening experience, not trying to objectively rate albums.

5.0=Masterpiece, all time favorite that is an incredible listening experience. No flaws or flaws are few and do not detract from the listening experience.
4.5=Favorite that provides an outstanding listening experience. Very minimal flaws.
4.0=Favorite that provides a great listening experience and replay value. Minimal flaws.
3.5=Favorite that provides a very good listening experience and replay value. Small flaws.
3.0=Good listening experience and replay value. Moderate flaws.
2.5=Average listening experience. What I consider an average commercial project. Flaws do not ruin the project but greatly detract from the quality.
2.0=Poor listening experience. Flaws outnumber the positive elements of the album.
1.5=Very poor listening experience. Flaws greatly outnumber the positive elements of the album.
1.0=Awful listening experience. Flaws are many and large, ruining the album.
0.5=Comically bad listening experience. Flaws create an album that is a waste of time to listen to.