I was alerted to this by fellow Internet Consultant Phil Bradley via his blog.
Unsafe search works by performing two Google queries, a normal query and a query with SafeSearch enabled. The set of ‘safe’ results is then subtracted from the set of normal results to yield only ‘unsafe’ entries. The idea behind Google’s SafeSearch is to eliminate p**n and other “undesirable” sites.
What is interesting about Unsafe Search is discovering what Google considers to be “unsafe”. The first test search I ran was on air quality. It yielded only one unsafe result in the top 30: the Idaho Department of Environmental Quality! A search on chocolate consumption came up with 3 unsafe results (one on chocolate is good for pregnant women, one on the potential health risks and a link to a Nestle forum). A search on gin vodka came up with no unsafe results in the top 30. Great! Now where did I put that cocktail recipe book?