Last month we reported the advertisers uproar after the launch of New AdWords algorithm. Lot of discussions have been taking place, regarding the time taken by Google to re-evaluate the score of the landing page once a page is updated. Of course, the discussion did not end at any concrete result. Then, the question came whether the Quality Score is based on the website or the whole Google account. The resonant reply was that it is based on the keyword and not the account. Though many people think differently.
To understand what Google is actually looking for it would be best to look up the recently updated page in  Google's AdWords Blog. Similar postings could be found on Google Webmaster Guidelines  explaining the attributes for organic rankings.