Indeed, the Seattle-based critic Tim Appelo, a blogger (for flixter.com), TV critic (for film.com), and art and drama critic (for the Seattle Post-Intelligencer), was once told by an advertiser in his former paper, The Oregonian, that each star Appelo assigned to a movie was worth $5,000 in ticket revenue.

Music critics, too, feel the pressure to make nice. In an era in which home-studio software and social networking sites have greatly simplified the production and the distribution of popular music, the sheer quantity of new releases by unknown artists has, among other effects, made it more tempting to accentuate the positive. Earlier this year, a critic at a national magazine wrote a capsule review of a new release from a suddenly voguish, previously obscure young singer-songwriter—and when pressed by a fact-checker, the writer admitted that he hadn’t listened to the whole album. What was the harm, the critic asked, as long as he was being positive? (Thanks to the fact-checker, the review was not published.)

“It is now the conventional wisdom among music critics that most reviews are three-star reviews,” says Ann Powers, the pop critic for the Los Angeles Times. “Everybody seems to feel like it’s become their job to be positive. There’s so much music being made, it makes sense for people to want to know what’s good so they know what to buy, but I’m not interested in writing that way. I get e-mails all the time from people who read my pieces, which are more essayistic than the thumbs-up, thumbs-down kind of thing, and they want to know if I think they’d like the album. I tell them, ‘I don’t know!’ ”

The culture of criticism in pop, a music geared to teenagers, is functioning more and more like the social economy of adolescence, in the opinion of a longtime rock critic who made the point on the condition of anonymity. “The world of music writing is becoming a lot like high school,” he says. “Writers do not write about music so much anymore. Their job is to look cool and to align themselves with the right albums at the right time so that they’re not belittled or kicked out of the cool club. I think that has really become a problem. People are afraid. There’s this fear that you could hurt your career or your image if you go out on a limb and say, ‘I don’t like The Hold Steady or Arcade Fire.’ So, for various reasons, people have decided to focus on the positive and be of good service to the readers.”

This is a school of critical thought with acolytes of many robes, and slow times in a field can justify overzealous advocacy as much as a boom can. In fact, critics in seemingly endangered areas of the arts (classical music, jazz, dance, independent film) can sometimes engage in boosterism out of a sense of purpose shared with the artists they cover—and, perhaps, a common sense of beleaguerment.

“There’s a great deal of trepidation and defensiveness in classical music writing,” says Greg Sandow, the classical music critic for The Wall Street Journal, who is also a composer. “Everyone’s afraid that they might harm the music, as if it’s a child who requires their protection.” Boosterism, he adds, is endemic: “In one case, I was with a critic who absolutely hated something and didn’t say so in print. I think that classical music sees itself as in some kind of danger—and it suffers from a sense of entitlement, so composers and producers sometimes squeal in outrage that the media is not covering their work. What I tell them is, ‘Go do something interesting. Make news. Then you might have a better claim for more coverage.’ ”

The higher mission of critics in all realms of the arts, formal and informal, popular and not-so, is, of course, to subscribe neither to pro-forma positivity nor negativity, but to confront the work intelligently and honestly, and to stir readers to thought and to feeling.

David Hajdu is a professor of arts and culture journalism at Columbia's Graduate School of Journalism.