One evening a few months ago, I had a conversation with a local San Francisco business owner about Yelp, the online business directory that lets users write reviews—both useful and completely irrelevant—of local business. We'll call said business owner "Robert." Robert mentioned that he received a call from a Yelp sales rep who said that for a monthly fee, Robert could have control over the reviews posted to his business's profile on Yelp. Robert told the sales rep to take a hike and never call him again.