Did you notice this: the format in which Google displays the adsense ads are different on its search results and on publishers websites. The ad displayed on Google search result is of the format: Title Desc URL But on publishers websites the format is: Title Desc Note that the URL is missing and so chances are more that the users mistake this to be content on the publishers website and click on it
Not true, it depends on the style of the ad banner. Some come with URL desplay and some don't. Dont recall exactly which, but I believe the big horizontal dont have URL and the big sidebanners do. The squares do have the URL as well. Google isn't trying to trick anyone.
The URLs are not available on horizontal banners but they are available elsewhere... no tricks.. just different forms of Ads.