Found this article: "Clicking hell: the Google way to bankrupt your rival" http://www.smh.com.au/news/technology/clicking-hell-the-google-way-to-bankrupt-your-rival/2006/01/19/1137553712078.html
As a person who spent over $100,000 on adwords last year, I'd say we didn't care about the search portion because I could measure results and they were good, but the content advertising clicks seemed bogus. Google couldn't tell us where the sites showed up, a lot of clicks "seemed" to come overnight, not during the day. There is a class action lawsuit about false clicks against Google going on now. As far as the posting above, Clicking hell, the GOogle way to bankrupt your company. You are able to exclude sites from showing your websites, such as your competitors and there are supposed to be protections on multiple clicks, but I don't think it is working. Fraudulent clicks are here to stay.
I think that the website exclusion only allows 25 site in list per campaign - so it is not efficient as is a big list to filter competitors but a small list for suspecious sites that brings clicks to your page. Also you would be loosing a lot of time adding suspecious sites every time.
I had the same problem that you're mentioning. My solution is create separate Campaigns specific for content and limit it for specific countries. Also pay less for the content clicks. Track the results and ROI is your friend.
There's gold in the content network, you just need to spend time weeding out the poor performing goegraphic areas. Start content campaigns in your country only, then add/monitor new goegraphic locations slowly and track the impact on your campaign(s).