tedster - 4:04 am on Sep 29, 2012 (gmt 0)
A link to an official communication from Google staff is fine - and this one comes from John Mueller, who was handson in SEO before he took the job at Google. He's been an excellent advocate for webmasters and a good communicator on the Google forums.
According to John, commenting on an explosion of 404 errors, it looks like this is the bottom line:
I'd look into what kind of add-on characters can be appended to a valid URL and have the new URL actually resolve. Then take steps to either correct the bad configuration, or add a line in .htaccess to at least NOT return a 200 OK for those artificially padded URLs.