Mass agreement does not create truth but only mass agreement

The Spectator offers sensible words about art and pretense which is relevant to issues being discussed here and elsewhere on "genius," "architecture as art," the "poetics of space" (that last one is a teeth-grinder for sure) etc:

Then I thought of all the tens of thousands of other tourists who had gawped at the painting over the years, muttering their appreciative noises. Could it be that the great majority of them, like me, were just pretending to admire it, simply because they knew that cultivated people were supposed to like Leonardo? Well, yes, I rather think it could.

And then I thought of a talk, heard many years ago at the Seattle Art Museum, given by Ivan Karp (?) of the OK HARRIS Gallery (?) --- (question marks only as I may be misremembering.)

It was an endearing talk. Karp explained his method of looking at "art," which, as the owner of a gallery, was his daily bread. He said that he would simply walk through a gallery or museum, not in a hurry mind you, but at a nice steady amble, and then when something would catch his eye, he would stop for a minute, at most. Then off.

Since it was exactly what I had been doing but had been embarassed to admit, I was pleased to have some external validation for a respectful but casual approach which relied on literally "what catches the eye" more than "this is good for you."

And then I also remembered seeing "live", in person, some work of art, some icon of "culture" and "erudition" --- yes it seeps down to the common-man --- which I had seen for decades in books and postcards and so forth to the point that I thought I knew it. Well when I saw it in front of me, "live," I had one of those "ohmygosh" moments which showed me that in fact all those decades, or even centuries, of praise for the work were well-justified. Sometimes indeed the experts are right.

The upshot? There may indeed be mass agreement on what is "great" in art and so forth. But it's as much social convention as anything else. That doesn't mean it's not, in social terms, extremely real and translate into spendable market value. And it doesn't mean that works which are said to be "of genius" may not in fact be so. But you have to and are allowed to make that decision for yourself. You can listen to "experts" opinions, sure, but just remember that it's just other people who said they are experts in the first place and there is, in art, very little penalty for being wrong except someone else's market value.

As far as I see it, art criticism is simply about predictions of future market value, which of course is based on what other experts says about market value. You might say it's an incestuous system.

As to buildings, one would expect that works by architects of genius would end up being more valuable. Is that so? How long does the "fame penumbra" last for a work by the architect-of-the-month?