Security vendor SiteAdvisor unveiled an online quiz Wednesday that tests consumers' ability to spot sites hosting spyware and adware.

Dubbed "Spyware Quiz" by SiteAdvisor, the 12-URL test covers five categories of sites notorious for distributing adware and spyware, including those dedicated to screensavers, smileys (emoticons), games, musical lyrics, and file sharing.

"We designed this to demonstrate how difficult it can be to tell which sites are safe," said Tom Pinckney, co-founder of SiteAdvisor. "Distributors of spyware and adware have become very good at making their sites look inviting and credible. That's dangerous because many people believe they can spot sites based on [their] look."

Earlier this month, SiteAdvisor rolled out free plug-ins for Internet Explorer and Firefox that identify dangerous Web sites as they're listed by popular search engines such as Google, MSN, and Yahoo. Safe sites are tagged with green icons, while red denotes sites likely to spew spyware.

According to SiteAdvisor, an average of 5 percent of Web traffic goes to red-rated sites, and the categories in the quiz -- screensaver, smiley, game, lyrics, and file sharing -- run red at two to three times the norm.

The plug-ins can be downloaded from here. For additional details on the inner workings of SiteAdvisor, check out this InternetWeek review.

Finally, SiteAdvisor's spyware quiz can be found on the SiteAdvisor Web site.