Let's review movie reviews. Millions read them. Actors covet nice ones. Studios scour them for positive nuggets to cram into advertising blurbs.

But how much influence do reviews really have on a movie's fate?

Virtually none on big action flicks and lowbrow comedies, which can pack in huge crowds despite rotten reviews. Family audiences and horror and sci-fi fans can turn out to see practically anything in their genre, no matter what reviews say.

Critics of critics say professional reviewers have snooty tastes, applying the same criteria to an Eddie Murphy comedy or Vin Diesel bust-'em-up as they would to a Kurosawa or Fellini film.

The Web has given movie buffs a broad forum to carp about traditional reviewers and post their own opinions, which often reflect more populist tastes than those of professional critics.

"You do wonder what kind of limited power we have," said USA Today movie reviewer Claudia Puig. "But we do it because it's a great job. I can't tell you how many people tell me, 'You've got the best job in the world.' When you love something, you're so excited to be able to tell people, and when you hate something, you love to be able to tell people, 'Don't see that.'"

It's in their passion for film — and their ability to scout out little gems — that professional critics hold sway.

This time of year, the awards prospects and commercial fortunes of many small films rest with reviewers, whose praise can help them gain a toehold among the holiday box-office behemoths.

Mike Leigh's abortion drama "Vera Drake," (search) Alexander Payne's road-trip tale "Sideways" (search) and David O. Russell's ensemble comedy "I (Heart) Huckabees" (search) debuted strongly in limited release on the strength of good advance notice from critics.

Unlike the gradual rollouts of old Hollywood, when reviews helped spread the word on new movies, summer popcorn flicks and other big releases now roar into as many theaters as possible, backed by colossal marketing campaigns to grab moviegoers over opening weekend.

"Movie reviews don't mean jack to summer blockbusters. It's pointless to even review it," said Will Smith (search), who has scored July hits with such critically drubbed flicks as "Independence Day," "Wild Wild West," "Men in Black II" and "Bad Boys II."

Smith struck again this fall with his animated hit "Shark Tale." (search) Trashed by critics, "Shark Tale" filled a void for family fare at theaters, with parents and kids rushing to see it.

Reviews were mixed on Mel Gibson's "The Passion of the Christ," (search) with many top critics loathing it. But no critic on Earth was going to keep avid Christians out of theaters, along with a more general audience intrigued by the religious firestorm the movie caused. "The Passion" took in $370.3 million, No. 3 on this year's domestic box-office chart.

This year's list of top hits is crowded with movies poorly received by critics, among them "The Day After Tomorrow," (search) "Van Helsing," "Troy" and "The Village."

A survey of 2,000 people by three business school researchers found that television ads and recommendations from others were the biggest influences on movie-going habits, each factor cited by about 70 percent of respondents. Professional reviews ran a distant third at 33 percent, while online ratings on such sites as Yahoo and the Internet Movie Database influenced 28 percent.

Sites like Rottentomatoes.com, which compiles reviews from professional critics but also Internet newcomers, have become more valuable to many consumers than the opinions of individual critics, said Chris Dellarocas, one of the researchers who conducted the survey as part of a study on how online reviews can predict a movie's box-office performance.

"I think there's a shift away from trusting the experts and more toward trusting the opinions of many," said Dellarocas, an associate professor of information technology at the University of Maryland.

If today's audiences are looking more for strength-in-numbers consensus than the voice of individual critics, the Internet still has advantages for reviewers.

Many astute critics have cropped up online who otherwise would not have had a forum. Newspaper critics who once had mainly local followings have found national exposure on the Web.

And sites such as Rottentomatoes.com or rival Metacritic.com provide cyber hangouts for film fans interested to read what critics in general have to say.

"It's the whole idea of united we stand, divided we fall," said Paul Lee, marketing manager for Rottentomatoes.com. "The Internet allows critics to come together and have collectively a bigger voice."

For their biggest releases, studios stage advertising blitzes and debut movies in as many as 4,000 theaters — two-thirds of the total number of cinemas — essentially buying huge opening-weekend grosses.

"Any film that can spend tens of millions of dollars on advertising can effectively obliterate any critical comment," said Los Angeles Times critic Kenneth Turan.

The year's two top-grossing films received almost universally favorable reviews. Yet "Shrek 2" owes its $436.5 million haul and "Spider-Man 2" its $372.6 million take to the fact they were sequels to enormously popular movies and hit theaters preceded by ubiquitous hype and promotion.

Commercial and critical sensibilities often run counter. Critics tend to savor high-minded drama and artistic production, while the average male viewer might rate a movie for its explosion and babe factor.

"You can't take a movie which is designed to be an action-adventure film and have it critically reviewed by somebody who's interested in independent, intense, dark, in-depth character portrayals like `Taxi Driver,'" said Nicolas Cage, whose adventure film "National Treasure" opens just before Thanksgiving.

Audiences may grumble that critics are snobs, but Roger Ebert of the Chicago Sun-Times said reviewers have to stay true to their tastes and let people know about worthy independent features, foreign films and documentaries lurking in the shadows of the latest blockbuster.

"You don't need a critic to tell you about `Titanic,'" Ebert said. "You really need a critic to tell you about good movies you might miss or might not have heard of otherwise. You don't need a critic to tell you the box office is right."

The one sure value of movie reviews is that they are part of the fun of show business. Reviews get people talking about movies, and sometimes, lead them to a cinematic jewel they never would have found on their own.

"Unless film is your life, you're going to be overwhelmed by the choices," said the Los Angeles Times' Turan, whose new book — "Never Coming to a Theater Near You: A Celebration of a Certain Kind of Movie" — is a collection of his reviews of cherished smaller movies. "You need a guide, and I think people are grateful to be guided to something they like, because otherwise, it's a crapshoot."