I think CK hit the nail on the head with his comments on Google’s policies:
Google AdSense – Program Policies Please note that clicking on your own ads for any reason is prohibited, to avoid potential inflation of advertiser costs.
What if the random ad served up by Google
interests me? I understand the reason they are putting up this rule,
but still, it seems like the very way the service is structured,
there’s a high chance that the ads running on my page will sometimes appeal to me more than anyone else visiting my site. Link: Sample the Web.