Hello Webmaster World, this is my first post after several years of lurking. I haven't used AdSense for years but I started a little side project a couple of months ago on which I run AdSense. It's a website with a huge number of mobile users (50% smartphone, 10% tablets, 40% desktop) so I'm very interested in optimizing for mobile. I use responsive web design techniques including the new responsive code for AdSense ads.

My first important observation was that the 320x50 Mobile Banners don't perform very well. Medium and Large Rectangles perform much better for me (which I think is kind of obvious). Right now my smartphone RPM is at about 70% of desktop RPM and tablet is 150% of desktop.

Second and more interesting, I found that the choice of optimal color scheme might be completely different for mobile than for desktop. I recently ran an experiment where I tested my tried-and-true blended color scheme against a contrasted one. Not surprisingly for me, the contrasted ads performed worse overall. Then I had a look at the per-platform results. On desktop the contrasted ads performed much worse. But to my surprise they performed slightly better on mobile.

I still have to run many more experiments to find out which colors perform best on mobile but my hunch is that it makes sense to use different ad styles for desktop and mobile. Unfortunately, this means to go back to Javascript-based ad slot selection for me. Did anyone make similar observations?