In my understanding, when you turn off content match, you don't turn off AdSense traffic that comes from the search boxes. Your ad just isn't displayed on sites but all 'em millions of search boxes keep on bringing you traffic.
I complain to Google all the time about search partner click fraud. Sometimes it is so obvious (many clicks from irrelevant AdSense sites), that the site is kicked out of the program. But the search sites in their network really bring in more fraud, and Google is reluctant to do anything about them.
The only reason I have search enabled is because of AOL. And to a lesser extent AskJeeves and Netscape. The clicks from AOL are so valuable, I would gladly pay three times what I pay for comparable clicks from Google.com.
If AOL ever starts its own PPC system, I will sign up immediately and continue to advertise on Google.com, but turn the search network option off.
They are hitting an obscure topic 100 times a day which is very high for my site and 98% of the traffic for the page. Now they want me to send reams of data which won't help because the clicks look fine but they simply don't make sense considering the topic.