We're always trying to improve.  Athletes, musicians, artists trying to get better at their craft.  If you were to tell a class of high-school art students what qualities to look for in a "good painting" how would you word it?  Is there criteria, regardless of the category (abstract, impressionist, realist, etc.), that could apply to a "good painting"?  
I'm constantly trying to gain understanding in the oil painting process.  The insights come as I work.  Painting constantly is a must for continued growth and I can see growth in my own work over the years.  As with many oil painters, I'm less happy with older work than more recent paintings.  In fact paintings that I thought "good" a while back can be an embarrassment now.  Is a "good painting" a personal best for the moment?  The history of art has many "masters" unappreciated at the time they lived.  Then to be labeled "Genius" years later.  Is a "good painting" then a product of current norms.  Like todays fashions, slang expressions, cars and sports teams is the title "good" movable?  That is to say...to be removed and placed on the next approved recepiant?  It's time for me to quit talking and get to work.  So I'm off to pick up a brush in search of a "good painting".  Best wishes, Jerry