How is this technique performed?

He's been doing this for ages, I don't know if some get banned, but I always randomly notice his site ranking for off topic keyphrases using subdomain spam.

http://www.google.com/search?q=site....mozilla:en-GB:official&hs=JGM&start=150&sa=N

Check deeper into the results to see some odd and disturbing keywords. So my question is wtf is happening here then.

Huge amount of pages indexed fyi nearly half a million - does google just drool over this?

no one know? over 500,000 pages indexed!