Here's a cool article in New Scientist detailing how search engines have put the hurt on content farms: "Inside search engines' war on bad results."
New Scientist magazine had computer scientist Richard McCreadie test how successful Google and Bing have become at fending off content-farm results. In both March and August of this year he ran a series of 50 search queries that are typical content farm targets, such as "how to train for a marathon." The results were "striking":
In the case of the marathon query, sites that contained lists of generic tips, such as "invest in a good pair of running shoes", were present in the top 10 in March but had disappeared by August, while high-quality sources, such as Runner's World magazine, now appear near the top. Similar trends were found throughout the 50 queries.
Much of the credit seems to go to Google's new search algorithm. Go read the whole article "Inside search engines' war on bad results." --WTP