I think it's unethical for Google (and others) to not do more to protect advertisers like Martin Fleischmann. IMHO, the best way to do that is by giving advertisers the means to protect themselves.

For example, let advertisers:

1. Limit clicks by country or region - it's easy to figure out which country an IP address originates from so why doesn't Google allow advertisers to limit clicks to specific countries or regions? Geo-IP mapping errors and use of proxy servers don't matter because they'll show up as hotspots when click frauders try to take advantage of them. So why not?
2. Limit clicks by time – most people don't get up at 3am to surf the net and those who do are good targets for sleeping pill or pillow ads. Why not let advertisers pick when their ads show? When combined with limits by country, click-frauders in Russia will have to get up at awful hours to earn their money.
3. Limit clicks by velocity – it doesn't take much effort to measure number of clicks over time per IP or IP-block. Why not let frugal advertiser filter out clients that generates abnormal number of clicks per day? I mean, how many ads does a normal person click on per day? 2-3? 24?

With all those PhDs, what's Google's excuse for not having offered such obvious (well, to me) protections?