Noticing a pattern here?
Paul Kedrosky, Dishwashers, and How Google Eats Its Own Tail:
Google has become a snake that too readily consumes its own keyword tail. Identify some words that show up in profitable searches -- from appliances, to mesothelioma suits, to kayak lessons -- churn out content cheaply and regularly, and you're done. On the web, no-one knows you're a content-grinder.
The result, however, is awful. Pages and pages of Google results that are just, for practical purposes, advertisements in the loose guise of articles, original or re-purposed. It hearkens back to the dark days of 1999, before Google arrived, when search had become largely useless, with results completely overwhelmed by spam and info-clutter.
Alan Patrick, On the increasing uselessness of Google:
The lead up to the Christmas and New Year holidays required researching a number of consumer goods to buy, which of course meant using Google to search for them and ratings reviews thereof. But this year it really hit home just how badly Google's systems have been spammed, as typically anything on Page 1 of the search results was some form of SEO spam - most typically a site that doesn't actually sell you anything, just points to other sites (often doing the same thing) while slipping you some Ads (no doubt sold as "relevant").
Google is like a monoculture, and thus parasites have a major impact once they have adapted to it - especially if Google has "lost the war". If search was more heterogenous, spamsites would find it more costly to scam every site. That is a very interesting argument against the level of Google market dominance.
And finally, Jeff Atwood, Trouble in the House of Google:
Throughout my investigation I had nagging doubts that we were seeing serious cracks in the algorithmic search foundations of the house that Google built. But I was afraid to write an article about it for fear I'd be claimed an incompetent kook. I wasn't comfortable sharing that opinion widely, because we might be doing something obviously wrong. Which we tend to do frequently and often. Gravity can't be wrong. We're just clumsy … right?
I can't help noticing that we're not the only site to have serious problems with Google search results in the last few months. In fact, the drum beat of deteriorating Google search quality has been practically deafening of late.
From there, Jeff links to several more examples, including the ones I mentioned above. As Alan alludes to in his post, the threat here is that Google has become a monoculture, a threat I've written about many times.
Now, is all this anecdotal evidence reliable? Perhaps not. What is worth noting now is that, half a decade after so many people began unquestioningly modifying their sites to serve Google's needs better, there may start to be enough critical mass for the pendulum to swing back to earlier days, when Google modified its workings to suit the web's existing behaviors.