What do these Ratings mean?
(A+) - If I was a record company, I'd release this. Perfect in almost every way.
(A) - I listen to this all the time, it sounds great.
(A-) - I listen to this all the time, but there are a few minor problems, usually not throughout the entire tape.
(B+) - I listen to this alot, but the problems are noticable and lasting.
(B) or (B-) - I listen to this once in a while, for a specific song mostly - too much noise to ignore.
(C+) or (C) - I listened to this once to see if the set list was right. I might listen to a specific song afterwards, otherwise it's too noisy.
(C-) or lower - I listened to the first song and then trusted the set list was correct. Yucky.

R.E.M.