URL Disappears from SERPS in incognito/private browsing mode

[jamesMP]

A product page I created last week was indexed immediately and has appeared on page 1 of google.co.uk over the weekend for its main keyword.

Checking the SERPS this morning, using Chrome's Incognito mode, the page was nowhere to be seen (on page 25 Google gave the "No more results..." message), although it was rank page 1 when I checked yesterday.

In "normal" browsing mode, the page still ranks #10 on page 1.

Testing in Private Browsing mode in Firefox yields the same results.

Does this mean that incognito mode fetches results from a different datacentre and it hasn't been indexed at that datacentre yet, or worse, it has been indexed and "dropped" from the results?

_{On a related note, the top 10 results come from just 4 domains (non of which are the usual big players/brands, and everything after page 1 is Russian, Polish, Lithuanian, Latvian, etc language sites selling the same product (shouldn't complain I guess, as it reduces the competition). Chrome actually tries to auto-translate some of the pages from Russian, etc.}

[vampke]

it means that google takes into account your personal browsing history.
incognito mode is a better way to get the real serps

[JS_Harris]

Unfortunately your visitors don't use incognito so a #10 ranking for one visitor is a #5 ranking for another and a #150 for another etc.

[lucy24]

it means that google takes into account your personal browsing history.

I was wondering about this. At first glance you'd expect your own site to come up near the top in your own searches, assuming that your sites are on topics you're personally interested in.

But let it go on long enough, and the search engine is bound to notice that you never click on results from such-and-such domain, even if the content seems a perfect match for your search terms. (You don't want to go there. You've already been there. You just want to see where it ranks.) So wouldn't they stop including those results?

[jamesMP]

it means that google takes into account your personal browsing history

That was my thoughts exactly, except that I use Chrome as my main browser, signed into all Google properties and keep Firefox "clean" for testing. So, when searching with Firefox it really shouldn't make any difference whether I'm in Private mode or not...