When I clear the caches and delete cookies I get identical search results for the terms I'm interested in on all of them.
Oh, and these search results have been pretty much steady as a rock with just the odd fluctuation for months now. Business is down for my sites at the moment but that's a seasonal/weather thing, nothing to do with any Google 'instability'.
You completely missed one of my points, so let me try to explain better since I did ramble a tad before -- No offense intended at all, just trying to explain why what you're stating really doesn't tell you much these days.
Let me use my personalization experience with Bing as an example, since they're what I use for "day to day" searches now and I'm more familiar with the little ins-and-outs of how it works and how long it takes to kick-in, etc. -- Just play along a pretend G does essentially the same thing.
When I'm coding and make what is to me a "navigational query" looking for a specific page on one of the "official docs" and there's no personalization the docs I'm looking for usually end up somewhere in the top 4 or 5 results.
There is often one of the two sites I *refuse* to visit above or just below the doc site and there is often another site or three I visit for similar queries fairly regularly but much less often than the official sites above the official docs site.
After somewhere around 5 queries [could be 10 -- not many]
and consistently clicking on the docs site [even though it's different pages on the docs site]
the doc site begins to show at number one for me. [To the point where if it's not number one, sometimes I'll mis-click]
More subsequent queries when one of the two sites I refuse to visit shows above one of the others I do actually visit and I click on one of the ones I do visit a few times, rather than the ones I don't, makes it so the ones I visit show higher than the ones I don't click.
Making further queries, where I continue to refuse to click on the two I don't visit when they "get mixed in" to the top results causes those two sites disappear from my results and there's a little message at the bottom of the page stating some results have been removed -- The removed results are the sites I don't want to visit.
One of my points in my "rambling, don't buy into it" post was if you have one of those two sites, or even one of the other ones I do visit on occasion, it doesn't matter a bit that whatever you do or how you do it to get "clean, non-personalized results" works, because I either won't see your site in my results or it will show lower than the sites I most regularly visit.
So, imagine if you ran one of the two sites I refuse to click on [I'm not saying you do, this is only an example]
, and I'll use the "annoying one" in the example: I refuse to click because the site tries to make me sign up for something before showing me what I was looking for and doing so is a turn-off. Then think about it being not only a turn-off to me, but [still an example]
also to a high percentage of other people.
When those other people who are annoyed do the same thing as I do [either won't click, or if there's an accidental click, return to the results as soon as it's realized what site was click on]
then the site that "with no personalization" shows in the top 5 fairly consistently across a number or queries doesn't show for any of us. Bottom Line:
It doesn't matter how clean your cache is or how well you "hide" to get non-personalized results, because personalization doesn't change those results. Personalization "happens on the way out" [at least think of it that way, because it's much easier to grasp -- just think "algo spits out the results", then "my personalization" kicks in]
and changes what real searchers actually see and what order they see it in, so neato if a site algorithmically ranks in the top 3 all-day-every-day.
When that same site "turns visitors off", once personalization "kicks in" real visitors don't see it any more, so the non-personalized results people try to get to "evaluate where they really rank" actually don't say much, except quit worrying so much about how to game the algo and concentrate on visitors if you want your site to show to visitors, because once "personalization kicks-in" the sites people don't want to see disappear or get moved lower in the results, regardless of where they rank without personalization being a factor.