Caan it work ?
Two aspects of this debate puzzle me. The first is that you can arrive on a porn site totally by accident, as happened to me once when I was looking for some CAD software on Google - I think the exact search terms were 'PCB design software' . This isn't even closely related to the 'Great tits' quoted earlier !
The second is that any form of control tends to be a blunt instrument. As a volunteer, I teach basic computing in our local library - yes, we still have one ! I was showing someone how to use a search engine, and it is more relevant when teaching if the student has an interest in the subject. In this case it was angina, this student suffered from it. Plugging 'Angina' into Google came up with the message 'Access denied, information of a medical or sexual nature' !
When I queried this, I was told it was for child protection. Following a complaint from me, this policy has now been changed. The public access computer in the childrens' area is now fully restricted, the five or six in the adult area now have, as far as I know, unrestricted access. I haven't actually tried to access my favourite porn site from the library - why should I ? - but I can get information on angina without restriction !