As an Internet user, I am one of the very few that could type the Url - percentage? from my experience of all the people I personally know that are not webmasters, way under 5% possibly - and even if I know how to do it, I do not see why I should, if not for personal grudge - therefore I think those who do not click on purpose on other people's website are not usually more intelligent than those who click, but more often that not envious.
As an Adsense publisher, why should I not click on other people's websites? To avoid a webmaster from receiving money from Google and the advertiser? But this is the soul of free trade. If this had any sense, in the real world we should NEVER look at shopwindows offering products and open the door shop... or watch a sports event that is sponsored since even if we do not want, the sponsor's message will get into our memory.