Critics, what are they worth?

A few places have been talking about the role of the critic lately. David Bordwell talks about "In Critical Condition" and the decline of film criticism (among other things). I just read a couple of books on criticism, Five Stars: How to Become a Film Critic, The World's Greatest Job by Christopher Null and Beyond Popcorn: A Critic's Guide to Looking at Filmsby Robert Glatzer (I recommend Five Stars even though it's only available electronically for $20 or used paperback for $80).

I am also reading the fantastic From Dawn to Decadence: 500 Years of Western Cultural Life 1500 to the Presentby Jacques Barzun. On page 73 Barzun is talking about the 16th Century and the way perceptions of art were changing:

Aesthetic appreciation is something more than spontaneous liking; a good eye for accurate representation is not good enough; one must be able to judge and talk about style, technique, and originality. This demand gives rise to a new public character: the critic. The future professional begins by being simply the gifted art lover who compares, sees fine points, and works up a vocabulary for his perceptions. He and his kind are not theorists but connoisseurs and ultimately experts. [italics his]

A good definition of a critic, if a lot shorter than Bordwell's.