These test pages have all been up and unmodified for over 2 years now so I doubt the Rank Modifying is at play here but I suppose you never know!
I'm seeing normal businesses with no SEO coming to me asking for help because their site has dropped out of Google! A few have sadly just gone to the wall but you can't put all your eggs in one basket (although the other baskets BING YAHOO ALTAVISTA and MSN are only small players now)!
It would just be really handy to get a feel for what makes a site stand out as quality. I'm finding it almost random from my own extensive research!