On moviescore.net, all ratings are on a scale from 1 to 10, where 10 is the best. Often the rating is represented by horizontal bars of different lengths:
There are overall ratings for each CD and single track ratings. Track ratings are relative to the score as a whole, and mostly on a rather rough scale with only even grades (2, 4, 6, 8, 10).
Original motion picture and television score CDs are rated with the following scheme:
Compilations of original versions/orchestral re-arrangements are rated as follows:
Compilations of non-orchestral re-arrangements are rated like this:
The score length rating is determined according to the following table:
(Double CD releases may receive more than 10 points for the score length.)
Unlike some other reviewers, in my opinion a soundtrack cannot (repeat: cannot) be too long. It is always better to have more rather than less music, since everyone is free to skip as much as he or shes likes, just by pressing an appropriate button on a thing called a CD player. Deliberately omitting score from a CD in the first place, however, possibly prevents everyone from listening to highly enjoyable music, and such I consider almost inexcusable...
You may notice that most overall ratings are actually quite good (>5). This might be explained by the fact that the author naturally concentrated on collecting above-average soundtracks. ;-)