A well known Zen saying tells us: “Willows are green and flowers are red.” It takes each aspect of reality for what it is, and nothing more. I think this is how one should evaluate bonsai. If it is good it will be obvious. If it is not obvious, it is not that good. However, all this doesn’t apply to people who can’t resist liking ugly things.
I recently made a couple of bonsai pots that would convey the feeling of wabi (rustic beauty) and I hope I succeeded to some extent.