I just visited a financial-related site and there is Adsense banner there. I saw two targeted ads before I dig into the details. After about one (1) minute, when I backed to the same page, the same two ads there but they just shifted the position between left and right.
I just felt a little curious. Did the advertisers change the bid in that short period? Are always the higher bidding ads are the left? Maybe someone just clicked one of them!?
I don't know. I would keep one eye on our site. Anyone noticed this before?
It's not jsut bids that determine positioning, but also CTR and how much of the daily budget has been used up. so shifting is entirely normal and desirable too, to give visitors a fresh picture (even if it's jsut flipping).