I&#x27;ll weigh in on morgante&#x27;s side here.<p>What WB discusses is a common misconception. Just because it doesn&#x27;t appear to work for yourself, doesn&#x27;t mean that targeting is not worthwhile. It&#x27;s not really designed for an improved user experience, but to provide an advantage to those running the ad campaigns.<p>The crucial thing that people forget, is that that targeting only has to be a little bit better than random to be worth doing (from the ad operations perspective). Given a large number of ads shown every day, with nominal cost, we&#x27;ve only got to push a fraction of those toward users with a slightly better propensity to interact to increase the interaction rate, and get paid more from the advertiser (presuming a model where the advertiser pays us based upon interactions that we generate).<p>One of the reasons that it is profitable is that the amount we might get paid for an interaction could 50p, £1 or even £10 depending upon the client and media. The cost of showing that ad is a few pence per thousand! So, we can get it wrong many many times, and still show a statistically significant improvement in interaction rates and make a huge dent in profitability for ourselves.<p>I discuss all of this in Chapter 5 of Algorithms of the Intelligent Web. 2nd Ed. <a href="https:&#x2F;&#x2F;www.manning.com&#x2F;books&#x2F;algorithms-of-the-intelligent-web-second-edition" rel="nofollow">https:&#x2F;&#x2F;www.manning.com&#x2F;books&#x2F;algorithms-of-the-intelligent-...</a>