In one of my high paying niche blog i get clicks but no money for them. In which cases the clicks are worth $0 dollars? My site is indexed in google.
Yes, they check for invalid clicks...especially if YOU are the culprit jk. I think alot has to do click value as well.
the clicks can be invalid also if there is an unusual high % of clicks per pageview. If there are 100 pageviews and 50 clicks it is very likeley that clicks will be listed as invalid.
Check your traffic coverage some times from specific region due to spam clicks Google also wont pay you nothing
I think there is no unique visitor of your site or you can get the same click with same ip address. may the click you can get is fake or invalid also.
In my case, I got lots of clicks and adsense just banned me. 2 - 8 conversion and my account go banned. Damned if you do! Damned if you dont.