TOS says you're not allowed to change the google code in any way.. howevery on this ebay-affiliated site uses a nice trick: http://www.marktplaats.nl click on any category google ads are shown at the bottom (in the past at the top where it resulted in even more in accidental clicks) they show the ads in their own css layout, but make it so that any click in the colored box becomes a click on the ad.. so you get a lot of accidental clicks..
Yea, some publishers get specials treatment from the amount of traffic they stream throguth their adsense.
i think they are premium publishers. premium adsense publishers has special rules. you need 20 millions page views to become a premium publisher