zarathustra2011 - 8:16 am on Sep 8, 2012 (gmt 0)
I've experimented with colours and placement, and sometimes it seems to make a difference, other times not. I leave it alone now, as I find the time invested in trying changes and experiments isn't worth the financial gain (assuming the experiment is positive).
I think I've reached a point with my site that doesn't allow for much more optimisation, and sometimes I refrain from slapping big ads in ugly prominent places just because it can make a website look spammy and unappealing. I think that's what saved me from Panda when it reared its black and white head.