ADSENSE CRITICISM

Abuse
Some webmasters create sites tailored to lure searchers from Google and other engines onto their AdSense site to make money from clicks. These "zombie" sites often contain nothing but a large amount of interconnected, automated content (e.g.: A directory with content from the Open Directory Project, or scraper sites relying on RSS feeds for content). Possibly the most popular form of such "AdSense farms" are splogs ("spam blogs"), which are centered around known high-paying keywords. Many of these sites use content from other web sites, such as Wikipedia, to attract visitors. These and related approaches are considered to be search engine spam and can be reported to Google. There have also been reports of Trojans engineered to produce fake Google ads that are formatted to look like legitimate ones. The Trojan Horse apparently downloads itself onto an unsuspecting computer through a web page and then replaces the original ads with its own set of malicious ads.

Criticism
Due to concerns about click fraud, Google AdSense has been criticized by some Search engine optimization firms as a large source of what Google calls "invalid clicks" in which one company clicks on a rival's search engine ads to drive up its costs. Some publishers have been blocked by Google, complaining that little justification or transparence was provided. To help prevent click fraud, publishers can choose from a number of click tracking programs. These programs will display detailed information about the visitors who click on the AdSense advertisements. Publishers can use that data to determine if they've been a victim of click fraud or not. There are a number of such commercial scripts available for purchase. An open source alternative is AdLogger.

Because AdSense adverts use non-xhtml compliant methods to display the advert blocks they will break xhtml strict pages. This is due to the use of the document.write method, which is deprecated in favour of DOM manipulation in xhtml, and the use of the iframe element, which is deprecated because it ties markup to presentation. This can be worked around by keeping the AdSense code in a separate html4 file served as text/html and including this in the application/xml+xhtml file using the object element.

Google has also come under fire for allowing AdWords advertisers to abuse trademarks. In 2004, Google started allowing advertisers to bid on any search terms, including the trademarks of their competitors. The payment terms for AdSense customers have also been criticized. Google withholds payment until an account reaches US$100, but many small content providers require a long time - years in many cases - to build up this much AdSense revenue. These pending payments are recorded on Google's balance sheet as "accrued revenue share". At the close of its 2006 fiscal year, the sum of all these small debts amounted to a little over US$370million - cash that Google is able to invest but which effectively belongs to its customer

ADSENSE TOOLS

AdSense for feeds
In May 2005, Google unveiled AdSense for feeds, a version of AdSense that runs on RSS and Atom feeds that have more than 100 active subscribers. According to the Official Google Blog, "advertisers have their ads placed in the most appropriate feed articles; publishers are paid for their original content; readers see relevant advertising — and in the long run, more quality feeds to choose from". AdSense for feeds works by inserting images into a feed. When the image is displayed by the reader/browser, Google writes the ad content into the image that it returns. The ad content is chosen based on the content of the feed surrounding the image. When the user clicks the image, he or she is redirected to the advertiser's site in the same way as regular AdSense ads.

AdSense for search
A companion to the regular AdSense program, AdSense for search lets website owners place Google search boxes on their pages. When a user searches the web or the site with the search box, Google shares any ad revenue it makes from those searches with the site owner. However, only if the ads on the page are clicked, the publisher is paid. Adsense does not pay publishers for mere searches.

How AdSense works
Each time a visitor visits a page with an AdSense tag, a piece of JavaScript writes an iframe tag, whose src attribute includes the URL of the page. Google's servers use a cache of the page for the URL or the keywords in the URL itself to determine a set of high-value keywords. (Some of the details are described in the AdSense patent.) If keywords have been cached already, ads are served for those keywords based on the AdWords bidding system.