In a very competitive keyword I'm monitoring on google.it, there's a guy using all kind of tricks ever invented.

He got #2 with an old blog (which wasn't related to that keyword), just adding an article stuffed with that keyword and putting thousands of links from spammy forums and blogs to his website.

In addition, a bit of cloaking let him show a landing page to the users, instead of the actual blog.

Some weeks ago his website disappeared from serps, I think because of a penalty.

Google has won against spam? NOT AT ALL.

This smart guy has set up a mirror domain (very similar to the previous) and, instead of doing a 301 redirect from OLD_DOMAIN to NEW_DOMAIN, he used the <link rel="canonical" href="NEW_DOMAIN" />

The result is: he's come back to position #2.

Maybe I'm missing some advanced blackhat techniques, but it seems this guy is simply "exploiting" something like a googlebot bug.