Yahoo has launched the beta of its McAfee SiteAdvisor-powered search security feature called SearchScan. Users can now opt to have potentially malicious results marked as such or omitted entirely.

Users in the US, Canada, UK, France, Italy, Germany, Australia, New Zealand and Spain now have the SearchScan tool turned on by default.

Similar to SiteAdvisor, SearchScan results which potentially contain browser exploits, viruses, spyware or adware are marked with a red "attention" sign. Users are also alerted when sites send unsolicited emails or share information with third parties. During the beta period, however, SearchScan will not include all McAfee SiteAdvisor "red" ratings. As of press time, there were 717,162 reviews in the SiteAdvisor database.

Settings to SearchScan may be altered to never display potentially harmful sites in search results, mark sites as potentially harmful, or show no indications whatsoever. When set to display all results except those deemed harmful, there is no notice that anything was removed from the results, it is simply omitted.

McAfee's SiteAdvisor application has been scrutinized for fair classification of "unsafe" sites, as some of the filters include less-defined criteria such as "Bad shopping experience," and some sites present a conflict of interest. Site ratings are submitted by a panel of reviewers, the most prolific of which are suspected by many to actually be spiders providing less-than-reliable information. Prior to McAfee's acquisition of SiteAdvisor, the system of site evaluation was largely supplemented by such bots.

Now, as a defaulted-on feature on one of the US' top search engines, many less-than-accurate classifications could remove legitimate sites from query results.