I am familiar with buying Adwords ads via CPM or site targeting, but can we tell if someone is buying CPM. I only see clicks and click related data in Adsense reports not paid impressions. Is it just rolled in to the eCPM?
Yes. I've noticed a few running on my site(s) when I checked my stats and noticed 0 clicks with associated earnings. If you get no clicks on a thousand impressions but have made a couple bucks odds are it's because someone is running (or ran) a CPM campaign on your site.