As a trained photoengraver who got to see all kinds of fine and commercial art, I've never been able to accept the artificial distinction between "fine art" and "commercial art." Plenty of really great work has been done for pay, esp. portraiture, and plenty of schlock has been done for the "feeling." Monetary intent is not a good measure of aesthetic quality.
I do think that Brian's statement that the depth and breadth of an artwork is what raises it to the level of "fine" .... and I've seen plenty of commercial work that ought to be at least considered, starting with Leyendecker, Flagg, Rockwell, etc.
Jeffery