PR blogger Jared Rivera unearths a restaurant in San Francisco that's essentially bribing customers with a 20 percent discount to write reviews of it on Yelp. Sure, it doesn't say a positive review, but as Gawker points out:
...But if you didn't enjoy your meal, a 20 percent discount on the next one isn't going to motivate you to do anything, including writing a Yelp review. Those who do write up a review will be inclined to add extra star-age, since they'll be presenting the review directly to restaurant staff. It all adds to an easy way for the restaurant—in this case, Mel's, an unremarkable 1950s style diner — to juice their online ratings.
Mel's Drive-In: 801 Mission Street, San Francisco CA 94103