If you play the AdSense game, whether you use it to monetize your exit traffic or if you use arbitrage aggressively, you need to know this information.
According to Brett Tabke of Webmaster World, Google can ID a click with a 95% accuracy. And just because they aren’t 100% certain that the click came from you don’t think that they won’t discount the click because they often do.
In fact, according to Google’s blog they said:
…chances are we’ve already detected your clicks on your ads and discounted them.
Basically, what I found is that Google knows exactly who you are and if you think you are smart enough by cleaning your machine, nuking your cookies, and using proxies, you are naive. Google tracks you and if you click on your own ads, it knows about it. They are punting people left and right for fraud more so than ever. They are also severing ties with webmasters that they have had relationships for a long time due to the information they have on these webmasters.
Google has discovered it is more of a risk than they care to take. Webmasters are crying, whining that their “cash cow” is being taken away and they did nothing wrong. Please. I have heard it time and time again. The guilty NEVER do anything wrong, do they? 
I will post the results of my test in the SEO Revolution (Closed Paid Membership).
The main reason I started the SEO Revolution was out of frustration. Frustration at all of the lies and misconceptions that are posted in forums, given as advice in teleconferences, and even taught in live workshops. "So why didn't all of this work?" " Why wasn't my site successful?" " Why am I still stuck in a rut?" 
So you are saying that everyone that gets booted from the adsense program must be guilty.. Who’s being naive? You said it yourself, people are being kicked off the system left and right.. Far too many for them all to actually be guilty.. And quite frankly, google should just ignore fradulant clicks. If it’s technology was so good, they could do that to ensure the safety of their publishers without taking the chance of booting potentially innocent people from the system.
Wayne,
This post is nearly a year old. At the time Google was booting a lot of publishers – and for good reason. Ignoring fraudulent clicks isn’t a solution. I have never talked with any publisher who was “innocently” booted from the system. No one is willing to admit what they were doing was wrong, just as there aren’t any guilty people in prison. Those types of comments are naive to say the least.
Sure publishers cry fowl that they were removed for no reason and they were victims. However, when their sites are analyzed, you see violations of the ToS, and the famous reply, “Now, how did that get in there, I didn’t do that.”
Hmmm. Sounds very familiar to, “That’s not my weed!”
I think all these words that Google have all the records of clicks bla bla is all words in books not perctical…
I think Google just take it psychological that the ratio on clicks on ads must be a very low because it is human nature…
I come to the point because with me there is a unique case,
God knows that I didnt make any click at my ads rather I visits my site after nearly after a month when I heard this news…
In a period of nearly two year, I earn nearly $350 from nearly 10 website and nearly 30K to 40 K immpressions average and get paid two time (nearly $100 , $100) only but while third time comes near then I got message from google that my account is diabled do two invalid clicks…
I didn’t understand till now that what happend with me…
There is not any huge amount of clicks or there is not any unpredictable traffic to my sites as well even then Google says that there are some invalid clicks…
Only one thing that the adsense weekly report I recieved earlier in the month that there is nearly 10 – 15 searchs and 9 clicks in a period of first week of April…
Who do this no one knows
I send them my website stats as well but nothing happend…
even then I get banned and my account is disabled…
But no one is to answer who is responsible for it…
The bottom line here is this is Google’s business and they can choose to ban anyone for any reason – or no reason at all.