Simple... 30% is not valid and therefore the account holder must be careful and examine his/her traffic and report it to google voluntarily if he/she found any abnormalities... When I got 21 clicks w/o any earnings, I reported it to google immediately..
If you know what the heck you're doing, 30% can be perfectly valid. I am currently stay around 16% myself and have been for quite awhile now. Once I switch to a dedicated server I will install open x to serve my adsense ads only a certain amount of times to a visitor and my CTR may hit 50%. Your statements aren't based on facts I'm afraid my friend. When it comes to adsense, SEO which results in highly targeted traffic is a no lose formula for adsense success. Also i don't remember him saying he didn't get any earnings for his clicks but I will reread to see if I missed something.
So you're in good shape. And making money. Heck I need to get some SEO tips from you LOL! I would love to get my CTR up to 30% across my whole network.