There's a superset, "All Music."

There are two subsets: "All Good Music" and "All Bad Music." "Good" and "Bad" are of course determined by the individual listener. No two people will have identical subsets.

Here's the rub:

There are more songs / compositions / performances in the "Good Music" subset than any individual will be able to hear in a lifetime.

So we have to cherish our time on earth and make decisions as wisely as possible.

And that's what The Riff helps us do--not just listening but responding and thinking and reconsidering.