McAfee's SiteAdvisor monitors the changes in search results and measures the level of what they call "dangerous" sites in all the major engines. Over the last six months AOL, Google and Ask have shown a decrease in "dangerous" sites, while Yahoo! and Microsoft have shown an increase.
The "dangerous" sites are those that have malware or spam. In May 2006 about 5% of all search results contained these elements, according to SiteAdvisor.
In their recent study they had found AOL, Google and Ask to have decreased their search results of such elements.
The same searches, last month, linked to 12% fewer sites judged risky by SiteAdvisor.The five search engines had 4.4% of their results tagged with red or yellow warnings by SiteAdvisor.
Chris Dixon, SiteAdvisor's director of strategy, said "when almost one of 12 sponsored links still clicks through to a risky site, there remains significant room for continued improvement."
The November report is available at SiteAdvisor. McAfee has been very thorough and the report is worth reading.