I have always thought that the most important thing Google can do, is to keep track of original content.
Google was in fact doing it much better until they started to deal with this through these new "Quality" algorithms.
From here on, I'm thinking aloud on their approach.
I feel that someone has to tell Amit (who I suppose is the Head of quality within Google), this approach of giving a guideline and asking moms working for third party vendors to rate results won't work. They can do far better than that.
1) If you want your machines to learn your users, model the machines on those users without giving them a guideline on what you think serves "quality".
2) To do it, make a fresh start and ask your users to rate results they click through for their queries.
3) A site-wide "block pages from this site" isn't useful either.Make it clear through your terms with webmasters that occasionally you would collect user satisfaction information for pages on their sites by framing them.
4) Occasionally frame the results for random users during unexpected times and locations (countries). Have a link on top of the framed result that would lead them to a rating page where they can rate it as "vital", "useful", "Relevant", "Spam", etc. Don't give them examples or make crazy suggestions like those relating to PPC ads and affiliate sites in the form of a guideline. A detailed guideline would never give you unbiased user opinion.
5) To make it interesting for users, give them points that can be accumulated in their Google accounts and redeemed for USEFUL gifts. :)
6) Use this data from the real users to model your machines and improve your algorithms.
Google might have different reasons for following the current approach and the above suggestions might or might not work. But if they really care about their users and willing to listen to suggestions, this could be suggested to Amit in Pubcon. Let me know if someone attending Pubcon will raise this before him. Pubcon is a great chance to grill or quiz the Google quality HEAD.
It is entirely upto google to make a choice but this approach might be far more useful and transparent.
The Quality team might be fairly new within Google but they need better approaches and direction.
I am just thinking aloud here and I might even be completely wrong but I guess this might work much better than what they do. Whoever released that confidential document in public domain must have been so upset with what they are doing. Most of the guidelines in that doc. doesn't seem to make any sense for quality.