This has been bothering me for a while and I was hoping to hear others' experience with this. I have noticed several strange things about Adsense reports, which are convincing me more and more that folks at Adsense are doing everything possible to conceal the payout information, even at the cost of reporting accuracy. 1. Cost per click: I have seen clicks from the same page bring from 0 (and yes, I'm serious, I've seen 0.00 clicks - once) to several bucks per click. During the same day, I can see first 10 clicks making more money than the following 50 clicks later that day. 2. Average cost per click accross several sites: Now, this is a real bummer. Presently, I have 3 sites running Adsense. The first site was a specialized local site, so I knew from the beginning I wasn't going to get much per click. That's exactly what happened. Then I added one more site whith relatively high paying ads. Then I added one more site with even higher paying ads. I'm tracking all sites with different channles. In the beginning the difference in CPC was almost 30 times between the first and last-added sites. After a month or two average cost per click is about the SAME on ALL three sites. 3. Page impressions. I was comparing my own page impressions stats to those of Adsense. I took one particular page on one of my sites as example. Adsense was showing about 40-50% less impressions than my own stats reported! Now, I understand that sometimes visitors have javascript disabled, sometimes Adsense doesn't serve an ad BUT we are talking about almost half! I'm in no way trying to say that we are being cheated out of our money. But I do feel that reports are misleading and misleading on purpose. Adsense support is very polite and prompt, but rarely helpful in answering the question. Usually I get something like "we have a comprehensive system in place, which ..." At this point, I see my Adsense reports as absolutely useless in terms of helpming me optimize ad performance. The only thing I look at these days is the total amount earned.