Yelp and Zagat: Do Customers Trust Restaurant Reviews Too Much? Bloomberg / Getty Images The Yelp Inc. logo is displayed in the window of a New York City restaurant Andrew Zimmern is not pleased with Yelp. The Bizarre Foods host and former chef recently slammed the user review site, saying it "essentially gives a tremendous forum for a bunch of uninformed morons to take down restaurants." Defenders of Yelp and other crowdsourced review sites, such as Zagat, Chow and others, say that the range of reviewers - some morons, some not - at least gives a broad spectrum of opinion, which is more than you can say for a traditional restaurant critic. MORE: The Top 10 Food Trends of 2012 But in my experience, Zimmern is right: the reviews are, at best, wildly uneven. In an earlier, more primitive stage of my food-writing career, I had the eye-opening experience of editing a Zagat dining guide for Long Island. I got to see all the reviews for every single place in the book. And guess what? Most of the reviews were utterly misleading. Because the reviewers generally tended to write up only the restaurants they went to frequently, they tended to grossly overrate them. Every strip-mall sushi joint had "the best fish this side of Tokyo!" that "you'd think just came out of the ocean!" The most loved and admired place in the whole area, with four or five times more reviews than anyplace else? The Cheesecake Factory. MORE: Restaurant Ratings: Is Michelin Lost in the Stars? I'm not trying to be snotty here, anymore than was the menschy Zimmern. I'm sure I grossly overrate my favorite restaurants, and underrate those that aren't to my particular taste, or those that I just happened to catch on a bad night. Most of the Yelp reviews I've read have been detailed, thoughtful, and fair-minded, as far as I can tell. But that's the problem. I can't tell you about all of them. I don't have time to read them all. Consider this analogy: Last night at dinner four very smart people, all of whose opinions I trusted, told me that Skyfall was bad. Skyfall! I was flabbergasted, but if I hadn't seen it myself, I might have missed the greatest James Bond movie ever made. Disclosure: I am a nerd. At a table of 10 people, four hated Skyfall. On Yelp, that would decimate a restaurant. To make matters worse, Yelp has the greatest influence not on the Skyfalls of the world, but rather the Beasts of the Southern Wilds and Moonrise Kingdoms. According to a study published last fall by an assistant professor at Harvard Business School, a one-star increase on the site leads to a 5% to 9% increase in revenue - except for chain restaurants, which spend heavily on branding and do not appear to be affected by Yelp reviews: "The impact of this information is larger for products of relatively unknown quality." In other words, new, small, restaurants, stumbling out into the world on unsteady fawn legs, have the most to gain - or lose - by foodies with starry eyes or an ax to grind. MORE: In Praise of the Endangered Restaurant Critic So what should a person do? Not use Yelp, or Zagat, or the rest? No, that would be dumb. The sites can be a big help, but you have to know how to use them. Ignore non-specific assertions of goodness or badness; even if you know who wrote the reviews and have reason to trust them, there's no accounting for taste, which is frequently uneven and always subjective. I, for example, have great taste in hamburgers and terrible taste in Thai food. But look for believable descriptions of service lapses - not "the waitress was unbelievably rude," but "we stood at the bar for 40 minutes before we were seated, despite having a reservation." Look for specific descriptions of dishes, particularly those that involve texture and temperature, two qualities I find unlikely to be wholly fictive. And, best of all, look at every picture you can. Because, unlike Yelp reviews, love letters, and professions of faith, pictures never lie. MORE: 10 Great iPhone Apps for Foodies