Books page policy

The Drupal books page currently lists all known published books about Drupal 6.x and 7.x.

As stated in that page, the Drupal Association gets some referral fees from sales on Amazon.com or from Packt Publishing sales (the DA gets more from Packt, so all their books are not linked to amazon). This has some shortcomings, among others the fact that those links are only useful to US-based visitors, but the solution for that would involve radically changing something in the way the page is built so that it could display an appropriate link related to the browser-provided or user-profile-specified location. However, that's not my question here (even though I'd love to discuss and participate in the solution for that).

The question I wanted to pose on this page is about which books get included on that list. As you know, it's now VERY easy for Joe Schmuck to write a few pages about Drupal, create a PDF out of that and send it to a self-publisher that in turn will list that in Amazon. There are already books like that for Drupal 6, and I expect more will show up for Drupal 7.

I've setup a policy that's written in a child page (http://drupal.org/node/383388), that self-published books shall only be accepted in the main list if proof of a technical review process can be provided (hopefully before "print", but OK afterwards).

The fact is that there lies the major service that a company like Packt or Apress provide: an editing process. Without that process, documents are usually full of typos and non-sensical statements.

As in any rule, there's a few exceptional cases:
1. Johan Falk's book Drupal 7: the Essentials was never technically reviewed as the rush to have it printed was one of the reasons why nodeOne decided to publish it themselves. I've spoken with Johan and he agrees that applying the existing policy, his book should NOT be on the list.
2. Dorien Herremans's book Drupal 6: Ultimate Community Site Guide which I've read seems to be a good enough book, but I don't want to put myself in the position of judge and executor, so my review doesn't count to put her book on the page.
3. Timi Ogunjobi's book Drupal 6 Site Blueprints is a terrible book that IS on the list, because for some reason Packt decided to publish it. He has a couple of self-published books that are even worse and their exclusion is one of the reasons why I've setup that policy in the first place.

The problem I have is that the policy is designed to prevent lower-quality works from being given a spot in a highly-placed search result on Drupal books, but a) it's not a perfect filter, as normal publishers sometimes disable their own quality filters; and b) it's actually keeping good quality books out.

So, my question to this group is what policy could be followed that:
a) I or who ever updates the page is not accused of denying income to a book author based on subjective arguments,
b) Does not rely on irrealistic expectations that the community will provide an effort to filter out the junk.

One possibility would rely on listing books with an amazon customer review average of more than 3 or 4. The problem with that one is that it's easy to game and changes over time, introducing maintainability issues.

Sorry for the long text.

João Ventura