Cool, since Tedster's moved us back on topic I'll post some more...
I don't think it applies in all situations.
Okay, true enough, mainly because nothing applies to all situations with Google, except they control most of the traffic and what works for some doesn't work for others even in an 'essentially the same' situation...
But what if they are looking to compare products from many sources?
I see what you're saying here, but when I ask myself is the best answer for Google the AdSense serving sites or the product comparison sites I think it's the product comparison sites, both from a Google and End User perspective... Users are looking to compare products from different sources and Google keeps the advertising budget at home, so to 'out-do' and 'rank above' I think in this type of market you really have to compete with some behemoths.
Interesting little note on 'product affiliate sales sites' where it might seem to be a good idea to be an Amazon affiliate... I read their TOS once and they reserve the right to create an 'essentially the same' site as yours if they want. I haven't read them in years, because I didn't sign up and won't, but it's something to look at if you think Amazon is a viable alternative to AdSense and don't want to give someone the right to copy your site if they feel like. Or maybe they're looking for something in a general category, but they're not sure exactly what it is. Then maybe you're a perfect match for their category, but they want to see other matches from the same category, and clicking Adsense is quicker than going back to Google and searching again.
True enough, but again, is it better for Google to present a site that is more of a 'summary', 'review', 'all-inclusive', 'directory' resource where people can either view summaries on the page or surf sites via banners, advertising, etc. or to send them to the 'single view of topic' site with AdSense or even similar advertising?
advertising in general is an inherently unsustainable revenue source.
* I honestly think the real answer to the result puzzle is: 'a mix is the best answer' and that's part of what has people a bit confused about some of the rankings, so see below this for an expansion of a slightly different take on things, and take what I have to say immediately following WRT style of site with a grain of salt. I really think 'flexible type of sites to show visitors' is part of the model they use, but that's only opinion at this time.
I don't think advertising in general is, but wonder which advertising site is the best answer for Google's visitors? The one that provides information about a single topic or the Amazon site(s) where there is information about a number of topics and products where you can surf and shop and be at the 'end result' you were looking for in a click.
I think one of the reasons people are so befuddled by the changes sometimes is the preaching of 'content is king' and while this may be true in some searches and settings, in others the opposite may be the case, so when people look at the results and say 'these results suck' because they have more content, information and text about a 'set of possibilities' rather than 'less about more' sites it could be they are 'going the wrong way' so to speak...
When you really think about advertising sites, how many are necessary in each industry or 'niche'? Most searches end on the first page, so 10 to 20 seems to be a really good answer and to compete in the top 5, again, it means competing and holding a spot against some behemoth sites that will probably not be replaced because they are expected to be seen by searchers...
When searching for a books or information about a 'major publication', how many people would think there's something wrong with Google in the US if they didn't have a choice to visit Amazon, read a review by the New York Times, buy from Barnes and Noble, or find information on a Wikipedia style site?
4 of the top 10 spot are taken by 'staples' in the results people seem to like and enjoy, so you have to compete with the other 1,000,000 sites with information about the topic for 6 places... That's not too much playing field for quite a few sites and a hiccup* could push you past #20 in the results.
* By hiccup I mean the top 20 out of 1,000,000 possibilities is .002% The same thing goes for other searches, like office products (Staples, Office Depot, Office Max)... You're playing for 7 out of 10 now...
The list keeps going, yeah there are more specific searches that will result in different results, but the point is in many cases there are 'expected results' and if your site fits the profile of Amazon you have to compete with them and every other site built on the same model for searches.
There's quite a bit of competition, and when I think about results for 'generic terms' and what makes sense, if their result model calls for 3 to 4 expected sites, 2 product comparison sites, 2 informational sites and 2 comprehensive review type sites in the top ten, then if you're the 3rd best informational site you're solidly on page 2 with no traffic...
If the model changes and there was room for 3 product comparison sites but now there's only 2 because the click data has changed what it says people are looking for then you could be the second best comparison site and in position 9, which is probably the worst spot on the page.
Do they use the 'type of site' model I'm referring to for generating the results? I would be surprised if they didn't use something like that or something similar based on the 'footprint' of the sites people visit most... It's fairly easy to do. Some people want information, most want to buy, quite a few want comparisons... Figure out the percentages, put the top sites from each 'style' on the first page and create a bunch of happy searchers who can find what they're looking for...