"New tallest skyscraper in the world" has long been recognized as a sign of impending financial collapse. I wonder if one could objectively evaluate "inartistic garbage selling for high prices", as a means of predicting the same? Esthetics is hard to rate objectively, but there would certainly be a consensus agreement on both of these examples.
My intuition tells me that the "new tallest skyscraper in the world" and overpriced esthetics aren't so much signs of an impending financial collapse directly, but they're rather a sign of financial security during the past several years. The problem is that the business cycles are... cyclical, which means that long-lasting financial security is likely to be followed by a financial downturn (collapse). Thinking about it more, I'm not even sure what the difference is.
Interesting point. There is a school of thought that frequent, shallow and short recessions are preferable, because if you don't have them you will pile up problems that all fallout during a deep, long depression. If this is true, then as you say, the skyscrapers, ridiculous art prices, etc. are just the most visible indicators of "lots of easy money, being spent stupidly", which is both a result of prolonged financial security and a bad omen.