I like the Chesterton quote 'where you draw the line'.
Where do you draw the line?
500 years ago, the chinese drew the line between amateur and professional : Art was amateur self expression, professional work had no more value than a cupboard or a pair of socks.
There is a similar divide in our modern appreciation of what is art and what isn't : art shouldn't be commercial, but we aren't quite clear about that. Do we categorize Irving Penn's and Avedon's commercial work as 'not art'? The romantic artist who lives off water and love, who lives to produce art only, is also a figure of ridicule.
Where is the line between kitsch and art? Someone made a reproduction of a Wylie Coyote cartoon cut out of metal plates, hung it on his wall calling it art. Is it? A friend's daughter justifies her obsession with make-up as an artistic endeavour, a search for beauty. Is that then also art?
Where is the line between very good artisanal work and art? Can a mass-produced camera be art? Is a hand-woven basket art? And if so, what makes this basket art, and the other just a utensil?
If a restaurant-bought meal can be described as art, what about a beautiful made-with-love family dinner? Is that not much more sublime, exalted, brimming with emotion than a T-bone from Sancho Panza's?
'I know it when I see it' is a perfect answer because it tells you nothing. I see a lot more questions than answers.