better ads for higher traffic sites?

is it more than just page content?

[RoySpencer]

We're seeing substantially higher CTR's in the last week, which I'm assuming is due to more "interesting" ads. We are also growing in traffic (up about 50% each month).

Anyone have evidence that higher traffic sites get "better" ads from Google? I know they give special treatment to sites with 20+ million page views, so obviously they have a way of sending ads based upon something more than just page content.

Any evidence out there?

[doingthistoolong]

Days I've had 50k+ PV's I have seen image ads show up...

[RoySpencer]

We almost never see image ads...I don't think they are responsible for the effect we are seeing.