Let's say, you just heard a modern written work or improvisation performed at the organ.
And, let's say, as far as you could determine, it had no sense of architecture, key center, or a clear beat.
The harmonies seemed to have no connection to each other, and dissonances, for the most part, were not resolved.
You can't remember it's theme and don't know for sure if it even had one ... or two ... or three.
It made a lot of sound, but it didn't thrill you, and didn't move you.
All you remember about it was that 1) it took off from the first note like a gaggle of geese and left you behind, then you had to catch up, and it left you a little lost briefly, 2) it was fast and loud, and 3) you were glad when it came to a stop finally.
At first, you don't know which side of the fence to come down on, deciding whether or not what you just heard was good.
Since it was fast and loud, and the performer/composer seemed quite satisfied with it, you're best guess is that it had to be good, even though you yourself can't make heads or tails of it.
Fast and loud always being good only applies to quick hanging, brightly colored wallpaper (photo).
Even then, it's hard to get used to it.