most small publishers have no control over there website visitors , so they cannot do anything to stop any fraud .. but such publisher have to pay for it .,.. so my suggestion to google is that donot cancel anyone's account , just reverse invalid clicks . or debit money for invalid clicks from affiliate's account ... in this way they can increase huge market share and may . and this will help publishers tooo ... affiliates take it as petition and sign it if you agreee .
Google is a company whose main motive as what I have heard is better end user experience. They have no concern for the publishers or even advertisers, I am an adword advertiser & if my site is poor quality, they raise the pay per click to unbelievably high prices. Thousands of people before have made a similar suggestion like yours to google as well. It is a private company, it conducts business on its own terms & by agreeing to their terms and conditions you agree & promise to comply by their terms or can be terminated at any time at the sole discretion of google without any reasons if they want to.
In addition to what ryanman suggest, I would like you to read the google philosphy proving the ryanman's statement true @ http://www.google.co.uk/corporate/tenthings.html
In addition with adsense google is known to ban adword advertisers as well. This is something not very popular but it is funny, as they can say no to even someone who is paying them money rather than earning money from them.
Yep, this shows how much serious google is about google adsense/adwords ...Plus i think it's pretty hard to check every single click... Saad
They have best tools and technicians in the business. I do not think with the brains and technology they possess it would be difficult to filter invalid clicks.