how my rating scale for things goes:
100- one of my favorites ever, perfect (S)
90- absolutely spectacular (A, A+)
80- i love this! great! (A-)
70- this is quality (B, B+)
60- this is good, take it or leave it (C+, B+)
50- it's okay i guess (C-, C)
40- kinda bad (D, D+)
30- i dont like this at all, not good (F+, D-)
20- truly bad, so bad (F)
10- truly terrible, like damn (F-)
0- either the worst thing ive ever heard, or so bad it transcends reality and is funny because of it (???)