Google's Different Stances on Click Fraud

It seems Google has been confused internally over their capabilities to protect pay per click advertiser from click fraud.

In a recent article in Bloomberg CEO Eric Schmidt says:

Believe me, as a computer scientist, we have the ability to detect the invalid clicks before they reach advertisers.

But the Google Adwords FAQ says:

If we find that invalid clicks have escaped automatic detection, you'll receive a credit for those clicks.

And the Google blog says:

When we believe those clicks are invalid, we reimburse advertisers for them. Some invalid clicks do make it through our filters, but we believe the amount is very small.

I have to admit I find it humorous that Schmidt says to trust him, because of his PhD in computer science that invalid clicks don't reach advertisers then other PhDs at Google say that invalid clicks do reach advertisers. Also, does that mean that Google thinks that there aren't PhDs working against them? Or how about just really smart people who know how the system works and know enough about web technology to be dangerous?

It may have took PhDs to create the first atomic bomb for 'peace', but it doesn't take one to turn into a weapon of war.