Music is good if it sounds like the musician wanted it to sound.

It is pleasant if the person listening enjoys it.

Schultz could convey emotion or make you laugh using a circle, two dots and a straight line for Charlie Brown's face. To achieve the result with such a small number of "tools" took great artistry. There are plenty of "proper" paintings that take 6' of canvas to say less than a Schultz cartoon.

Martin Hayes can play the same tune 5 or 10 times through, unaccompanied on a fiddle, and it gets better each time through. Is a solo fiddle playing simple 2 x 8 bar folk melodies less valid than beethoven?

Motörhead stick to the standard drums, bass, guitar, blues-based hard rock format, and can still fill venues and sell new albums after 30 years. Someone likes it - including me.

My CD collection ranges from William Kimber, to Slaughter and the Dogs, to Modern Jazz Quartet. Most of it is "good music" in that it says exactly what the musician wanted to say, and "good music" in that I enjoy listening to it.

I also have some "bad music" in my collection - live recordings of inexpert punk bands with obvious glaring breaks and stumbles in the rhythm, and the musicians being out of time with each other. On the other hand, I have some excellent punk music that many of the people in this forum might regard with scepticism.

It's nothing to do with how complex a piece is, but all to do with how well executed it is.