“Adsense Ghost Clicks” is how I call them, clicks that don’t earn anything. Did it ever happen to you that you login into your Adsense account showing a certain number of clicks and after refreshing the page you have some more clicks but the revenue is still the same as before? I made some research on this topic because this happened also to me more than once and I finally found the major reasons of Adsense Ghost Clicks.
1 ) When you added a new Adsense to your website, you forgot to unhook the “show public service announcements” option.
These kind of ads are also called PSA and are some sort of “free advertisements” to fill your ad space in case there are no paid ads available. Clicks on these ads are registered in your account but you are not paid for them. This is the first reason why you sometimes see your clicks increasing while your revenue remains the same.
2 ) You clicked on your own Ads.
Google Adsense has a very good tracking system and they know if you click on your own advertisements. Many webmasters think that Google won’t ban you anymore for clicking on your own ads but they will simply don’t count them. In fact the ufficial Google Adsense blog recently wrote:
We do understand that an accidental click may occur from time to time, so there’s no need to contact us each instance this occurs.
3 ) Invalid clicks.
If one of your visitors is clicking more than 1 advertisement, Google will probably consider those clicks invalid because they come from the same IP adress. Google will also consider them invalid if the clicks come from questionable sources (a bot made to click advertisements, for example).
4) Clicks from foreign countries.
Sometimes it happens that the language of the ad, differs from your website language. Google is using “Geo-targeting” but their system is not perfect. If you have an english page but a chinese ad will show up, clicks on this ad will be considered invalid clicks (this is only a theory yet).
5) Google does not charge the earnings at the same time as the clicks.
This is another theory I read about…it never happened to me but it seems like this could happen if you recieve a huge amount of daily clicks.
6) CPM advertisements.
These are advertisements that pay you for each impression and not for the clicks they recieve. Clicks will be counted in your Adsense account but your revenue will increase only by increasing the impressions and not by getting more clicks.
This sould be all reasons that bring “Ghost Clicks”. If know some more, drop me a comment and I will add them in this post (giving credit to who suggested them 
)