what is the difference between good and bad music

Good music evokes an emotion consistent with the music. The emotion may or may not be one you welcome at the time. For example some may not like listening to sad songs because they find it depressing, but that does not make it bad music. Bad music fails to be convincing or credible enough, or familiar or fresh enough, to get under the skin enough to unleash that emotion.

Again Mrtennis, I am describing how good and bad music occur to me. I am not describing how they occur to you. Yes the same piece of music may be good one day and bad the next, based on my emotional state, just as a pill might be good to take one day and bad to take the next because I had a headache on the first day and not the next. the pill is the same but the context isn't. A car is good for getting to work but not good for getting to Europe. I have no problem with that. Do you want some objective way to put a label on a piece of music that forever says it is good, and ve haf vays of making you like it! What makes you want that?

Blue isn't better, green is!