This cracks me up... G00ble is looking for "quality" but if you search for a product keyword all you get are shopping links, the websites that provide good product reviews are on the 2nd and 3rd page... G00ble is a corporate entity and they are only concerned about profits, whatever it takes to maximize shareholder value regardless of what the SERPs bring to users.
One possibility is the percentage of ad space on the page might matter (not strange given scrapers/content farms often have a high percentage of real estate going to that).
A quick check shows the ones that lost rank devoted google's limit of 3 ads per page while ehow devotes only 2.