Plenty of things happened during my holiday. I got email from Google that my AdSense account is closed due invalid clicks. Well, I can not do too much if someone likes to support my site and clicks around too much. I did not want to put "Terms of Usage" agreement to pop up before user can see any content. There was no reply from Google to my response through their forms, so I decided to remove advertisement code from templates for good. Maybe it is better this way.

It just made me think a case where those AdSense clicks bring significant income to the site owner. In my case it was just pennies and interesting hobby. But for someone with more serious goals it can ruin a lot. This also makes possible to blackmail site owners. In this forum there is some discussion about this topic. I have read elsewhere that there are tools to track clicks on ads and then blacklist IPs based on suspicious usage patterns yourself before Google's own alert is triggered. This might be necessary for all site owners with AdSense as Google does not warn owner of the possibility of account closing.

This event was naturally disappointing but I learnt something about how these things work. If I ever happen to set up a commercial site with serious traffic I wont count too much on AdSense income longevity.