max - no, it's not personalized results, I have that turned off and I am signed out of my Google WM account. I was on the road this last week and did some searches on a Best Western wifi network about 300 miles from home. I show the same high listings there too. I also use audio "doorbells" on my key pages, my home page, order page, and other main info page of my site. Those doors bells are very active at some times, then very quiet at others. I have been using this system to monitor my sites for nearly 10 years and I can tell what my site is doing without even looking.
As far as using sales frequency to represent SERPs, I respectfully disagree with another post that ties sales to something else. I think SERPS and sales are very closely tied. Yes, we are in a bad economy, but for 10 years I could tell the time by my sales klaxon. Sundays were usually 1 or 2 sales per hour all day. Now I get these "windows" of sales only minutes apart, then hours of nothing. It's as if Google can turn us on and off while still showing our site in the SERPS. That is very strange and an experience shared by other sites over in the UK. I am in the US.