To continue with poloniculmov's comment, the classical music you are listening to now is the 'good' stuff. If you go and study manuscripts of music that isn't played any more, it's for a good reason. Take Salieri's music for example, it's fairly bland (though the odd piece stands out).

Then we have some crazy music like Gesualdo - his music is quite frankly bizarre to some modern ears (those who have't been exposed to much 20th century music, anyway - I love it). A great film on this by Herzog:

http://en.wikipedia.org/wiki/Death_for_Five_Voices

I also like classical music, but that surely can't be a good foundation on which to judge various forms of art.