dontono7 - 7:18 pm on Oct 27, 2011 (gmt 0)
I've often thought something like that was happening too. However, I have come to the conclusion that it is just a matter of how many people are advertising currently, and what the best available "fit" would be for your site/page at the moment. My CPC and CTR also vary widely, from one day to the next even. Anybody else have this experience as well?