No absolutes for me either, good vs. bad.
And there is music I enjoy and music I do not enjoy.
But I still try to stay open-minded and would not criticize what someone else likes / dislikes.
So for me, being open-minded in no way implies you love every single piece of music that exists.
I agree with this, but look at it from a different (possibly more pessimistic) angle:
I think there is a diffinative good/bad music, but what meets the criteria for each (and what that criteria actually is) is entirely up to the listener of said music.
...and that's ok. As a player, I'm sure a lot - that is, most human beings - would think my music was completely lame. Maybe .0001% of people would dig it. Doesn't bother me, since I do it for myself and not as a pro doing it to make a living.
One thing I can't really stand (and am guilty of myself from time to time) is listeners lumping entire genres into into the good/bad category. I'm not a rap fan, but that doesn't mean there aren't a handful of guys out there making really interesting beats and engaging provocative subjects beyond boats & hoes. I like heavy music, but that also means that not every kid who bought their first guitar last week and is convinced they can play Black Dahlia Murder through a Spider IV should be considered "good."
tl/dr; it's okay for people to like or not like whatever music they want for pretty much any reason(s) they might have, but good musicianship tends to rise above preconceived notions.
EDIT: on the other hand, what is music really? An organization of tone/timbre, rhythm, a collection of pitches in time to form some sort of melody... What *might* determine good/bad, on a subconscious level, could be cultural, or perhaps simply the interaction of noise stimulus to the (widely varied) human ear?
A jet passes overhead, a flag flaps in the wind, boots on a busy sidewalk, and all of a sudden August Rush is composing a classical piece with a flamenco vibe.