I just noticed I posted after the maximum thread length, although, despite the warning that additional posts will not be threaded, it always seem to work. In case it's true, I wanted to add to that interesting discussion on what is good or bad. Plus, this will give the thread new life. Anyway, here is where I went:
think a post-modernist might argue that there is no bad art, except for their critiques of modernism.

But first, the example of Van Gogh is interesting because I think the "discovery" of his hidden genius is part and parcel of his mystic. Laypeople's fascination with Van Gogh's reassessment is measured in dollars. In the artworld, he is valued as an important relay in the history of modernism. In his time, his value as a modernist was already evident, not to the official salon artists of the time, who were having a totally different kind of dialogue, but apparent to the growing modernist movement.

If there is any context rigid with absolutes, it would be modernism. Because modernism's roots are found in the renaissance, imo, modernism was able to rake in generations of artists into the domain of modernism, right up to today. At least half of all works have been assessed through modernist concerns--what is good, what is bad. I say half, because the other half has been interpreted through the lens of the post-modernist. Except fot the post-modernists' general distain for modernism, it's rare that they pronounce any any as bad.

The zeitgeist of our time has not been the re-evaluation of what was once-bad as now-good, but more often the turn toward what was once-good is now-bad. Maybe, even more cynically, what is now-good is also now-bad.