<i>&gt; When a bunch of reviews can undo the effects of a massive, weeks or months long marketing push, I&#x27;d say it&#x27;s time to rethink your product strategy.</i><p>Whenever a debate about advertising pops up on HN, many people defend it as the necessary way for consumers to find out about good products. Healthy free markets depend on informed consumers, but to think that advertising results in informed consumers makes little sense. I find it strange that a community of logic and science oriented people can hold such a notion.<p>When communities were small, reputation was king. If your town had two bakers, everyone knew which one was good and which one sucked. No amount of advertising would fool the townsfolk into going to the sucky one.<p>But this doesn&#x27;t scale to huge cities with tens, hundreds or thousands of choices. We can&#x27;t know the reputation of such a wide array, and we can easily be fooled by advertising. Internet-based recommendation systems make the grapevine and reputation scalable. I hope we see more innovation. Yelp is a start, but it fails miserably because if I rate a place 5 because I love very authentic Thai food, and another person rates it a 1 because they are used to Americanized Thai, the restaurant gets a 3 (I&#x27;m simplifying for illustrative purposes). In other words, Yelp&#x27;s rating is useless to both me and the other person.<p>I&#x27;m hoping for a future where recommendation systems and collaborative filtering get so good that they render marketing and  advertising useless.