from trillianjedi's post...
since the top paying ad appears on top, and the lowest one appears on bottom... suppose the payouts for the 8 ads are as follows: 42c 41c 19c 18c 11c 10c 4c 3c
if you have one block of 4 ads in a prominent location, then you isolate the higher-paying ads. if you include a second block, regardless of how you code it with CSS, then the CPC of that second block is significantly lower than the first.
as i understand it, a click on the top ad on the second block will be 11c, no matter what you do. for some publishers, it makes sense to limit the number of ads that appear on the page to increase earnings.
am i missing something?