Five-star fakes

The evolving fight against sham reviews.

For as long as there have been online reviews, there have been fakes.
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The problem is particularly irksome for sites dedicated to offering reviews, such as Yelp and TripAdvisor. Amazon sells everything from books to lawnmowers; Yelp’s main offerings are its 83m reviews. “If consumers can’t rely on the content,” says Vince Sollitto of Yelp, “then the service is of no value.”
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Expedia allows hotel recommendations only by those who have paid for a room there. Amazon tags a review as “verified” if the writer has indeed bought the product.
http://www.economist.com/news/business/21676835-evolving-fight-against-sham-reviews-five-star-fakes