For example, if somebody made 5 or 6 clicks in one visit, and never again, does one have to report this? I just had a visitor my statcounter could not find and it looks like his/hers 6 clicks brought over $11 to my adsense... Should I report this as an unusual activity?
I would simply screenshot the info from statcounter and your adsense page and send it to them and let them decide. quick and simple hard evidence
i agree to dkhargroves, just provide a screenshot so that google can have a better idea on what really happened to your account.
no it is not unusual, I sometimes visit a site and start clicking ads if they are interesting or if I have seen the ads for the first time.
good point sharmilee1, you may need to consider it a pat on the back. If the clicks are genuine, you have written good content based around your ad keywords! Better safe than sorry though, might want to let Google check it out
Let the google decide, google consists of smart people and they have their own system of determining click fraud.