" Evidence shows that even the most highly ranked rival service appears on average only on page four of Google's search results, and others appear even further down. Google's own comparison shopping service is not subject to Google's generic search algorithms, including such demotions."
I didn't. "Doctoring results" sounds to me like modifying the ranking of organic results to demote those services, which is not what that sentence says either.
> Google has included a number of criteria in these algorithms, as a result of which rival comparison shopping services are demoted.
Sounds like a jump to conclude they were doctoring results from "they modify their ranking algorithms".