How do we know if a painting is "good" or "bad"? Well, we don't really. I mean, there isn't a definitive, objective scale to measure art on.
This impossible conundrum of judgement, one way or the other, leaves painting awash in an ocean of art debris. Paintings crashing into paintings. One painting (or sculpture) that looks awesomely stupid might fetch millions at an auction and another that looks interesting may well hang unsold on a gallery wall. The "experts" (writers, curators, gallerists, never artists!) often flog paintings for reasons that have little to do with merit and have a lot to do with social connections, money or just lack of insight.
It's a bit of a mess.
My late and great painting teacher, Sam Tchakalian, knew painting better than anyone I have ever met or read. In a critique one can watch online, Sam is critiquing student work. He asks the students if they want to make comfort paintings or challenging paintings. He doesn't mean that all comfort painting is beautiful or that all challenging painting is ugly.
This analysis itself is challenging.
(In his own paintings Sam's colors are beautiful. But his paintings are never comfortable. The paint is as thick as cake icing, the squeegee marks are insistent, slashing even. The effort seen in the paint application is both aggressive and ballet-like. They do challenge us-there is a price for admission. We have to find our own way into the painting so that it makes sense, on its terms. His paintings challenge us to read the language of paint and this is where knowledge of painting is the price of admission.)
So what does Sam mean by comfort versus challenging? We've all seen comfort painting. Paintings that hang mutely, no way in and no way out. There's no way in because there is no where to go.
A challenging painting takes us to a place we aren't sure about. We have to read paint like we read English. We have to read the language of aesthetics. We have to be curious. We have to open the door to enter...the painting.