Keyword stuffing with camouflage (hidden) text on the bottom of the page. Amazing, how they are ranking. This trick used to work well back in early 2000 whorehouses.com Mates, What's your Take???
Like you said, it used to work...not anymore. Google is smart. You will be penalized by google if you try it.
Google now is always updating their algorithms. I you do that thing on your site you'll be sorry Google is very smart.
So how could they get away with this old seo trick? Google doesn't see the keyword stuffing text is camouflaged?