I've seen a bunch of the same style popping up lately. Something like...
[navimg] navlink / desc
[navimg] navlink / desc
[navimg] navlink / desc
[navimg] adsense
[navimg] adsense
[navimg] adsense
... where navlink / desc has the same format as AS.
As for a percentage, on these sites, I would imagine as high as a majority of the clicks would actually be accidental.
How many would realize that they just clicked on an ad is (I feel) another important statistic.
As for accidental clicks throughout the whole AS network... less than the tricky sites but certainly not negligible.
What would you look for in your AW traffic stats to find such clicks? Visit time would probably be big, how much of the page is actually loaded...
