Oh I totally agree, there is an onus on them to be more transparent about what they are doing. The scale is what I find amazing. I don't doubt that clever spammers will sign up a couple of million AdSense accounts over a weekend, and try to pull some click fraud pennies out of them. It is just too tempting a target for "free" money. If you recall there was an event where Google would deposit a small amount of money in an account, and you had to verify the amount to "prove" you owned the account, and some smart chap started creating thousands of bank accounts and accounts and when the pennies got deposited withdrawing them and closing the accounts. I believe it was Brad Templeton who said "Give me a way to steal a penny over the Internet and I'll show you how to make money fast."

That is the challenge I see Google facing, on the one hand AdSense is a thing, on the other its prone to fraud.