Spam Clock illustrates the problem of link relevancy for Google, Bing, and other search engines
Spam Clock just scratches the surface of the problem, though. The real story is about spam and scraper websites making money from the hard work of other sites. These sites place highly in search results -- sometimes above the real websites -- and make money from Google AdSense -- it's all a little bit convoluted. Hopefully search giants like Google and Bing are working on a solution, but it may just be that the Web is finally growing too fast for conventional indexing.
This may also be one of the strongest signals that link sharing through Facebook, Twitter and other social sites is the way forward. Imagine searching an index of your friends' favorite ('liked') websites, rather than a spam-ridden search engine index. Today, our social graphs might be too small to cover the entire Web, but in a few years...
Update: In an interview with Adotas, the CEO of Blekko (the company behind Spam Clock) says that the spam calculation is "an extrapolation based on the growth of the web and the fraction of spam that we're seeing."