A study from McAfee found that seven percent of all sponsored links bring clickers to unsafe websites and for the most popular search results it's 4 percent:
The practice of unbridled clicking becomes riskier for Web searchers focused by so-called "sponsored results," the paid ads that appear alongside targeted search engine results, the company found. Nearly 7 percent of all sponsored ads brought clickers to risky sites, according to the study.
The study was meant to highlight McAfee's free SiteAdvisor tool. The free add-on for the Firefox and Internet Explorer browsers tries to give Web surfers a bit more intelligence about the safety of following links returned by the Web's top five search engines.
With the software installed, each search result listing is accompanied by a small color-coded, green, yellow, or red icon. SiteAdvisor occasionally will give a question mark to a site it hasn't developed an opinion about that site's security. A green check mark next to a result shows that the software hasn't encountered anything questionable about the site. McAfee grades sites with a yellow X to encourage a Web surfer to use caution. If a SiteAdvisor-aided search result earns a red X, McAfee has received reports of scammy, spammy or outright malicious activity emanating from the site.