The most common frustrations among AdSense publishers are 1) Google serving inappropriate ads on their web pages, 2) low click-through rates and 3) low payouts per click. This article discusses the first frustration, which is highly correlated with the other issues, and discusses what webmasters can do to combat it.
To begin, it is important to understand how Google determines what ads to serve via the AdSense program. This explanation goes back to April 2003 when Google acquired Santa Monica, CA-based Applied Semantics. Applied Semantics? products are based on its patented CIRCA technology, which understands, organizes, and extracts knowledge from websites and information repositories in a way that mimics human thought and enables more effective information retrieval. A key application of the CIRCA technology is that it allows Google to, without human intervention, understand the key themes on web pages in order to deliver relevant and targeted advertisements.
However, the CIRCA technology is not always accurate or appropriate to the page. For example, in a general web page about health topics, AdSense is currently serving ads for insulin even though only two words in one paragraph relate to insulin. Rather, the site is much more focused on dieting.
One explanation may be that the CIRCA technology is tied to keyword pricing and inventory (e.g., AdWords(TM) advertiser daily budgets), and that AdSense serves ads that it hopes to maximize revenues. However, this often violates a critical AdSense rule - if the ads do not relate to the topic discussed on the web page, visitors will not click on them. Likewise, TopPayingKeywords.com always tells clients never to try and trick AdSense. That is, if customers are coming to your page from a link or advertisement for one topic (e.g., hair styles), never try to create a page about an unrelated topic (e.g., mortgages), just because that unrelated topic is an expensive keyword. While you will be serving expensive ads, because the topics are not correlated, visitors are unlikely to click on them.
Getting AdSense to serve the correct ads is a trial-and-error process. In the health page example above, all it took to get AdSense to remove the insulin ads was to remove the paragraph in the text that mentioned insulin. Fortunately, AdSense often updates itself within just a few hours, so it’s easy to keep modifying your site until the most relevant, and hopefully most expensive, ads are served.