Often, it seems experts and critics are at odds with the general public as to what works of art are good; many well-received films have performed poorly at the box office despite marketing, for example, while many blockbusters have been derided by film critics.
What is going on, in these cases? Is it just a difference of opinion, and if so, why is there such a role as a "film critic"? Or do critics detect quality that the average moviegoer can't, and do they see through the presumably shallow pleasures enjoyed by moviegoers?
How is it even possible to tell the nature of the disagreement in these situations?