Welcome to WebmasterWorld Guest from 188.8.131.52
I think Google is clever enough to not confuse link checker bots with fraudulent clicks.
If not, this would be a very easy way to harm your competition.
You have nothing to worry about running any linkcheckers on your site - they don't "see" pages the same way a browser does.
There is one line mentioning the address ht*p://pagead2.googlesyndication.com/pagead/show_ads.js
The status for such address is "forbidden request"
So, it looks like Xenu tries to follow (only once) the AdSense link.
Among a few hundred other lines, there is only one other occasion when this status shows again, and it is when Xenu tries to access h*tp://directory.google.com/Top/Computers/Internet/History
I donīt have any other link pointing to Google.
So, it looks like Google recognizes the request as being from Xenu and (cleverly) ignores it.
Would be silly if i did, so don't worry your doing nothing wrong, or harm to your account