Should Adsense Blend or Stand Out?

I guess that's a loaded question. It depends.

In my personal experience, I've had success both ways. However, I have noticed a bit higher CTR when I changed from ads from blended to a color that complemented the page's design, but stood out.

The page was mostly blues, so I chose a couple complementary reds for the ad design. The CTR went up a little bit when I did this. However, I'm not sure if that's really due to the color change or just more traffic. Who knows?

I submit that a big problem with Adsense (and ads generally) is ad-blindness. Users (especially regular readers) just become blind to ads over time. Perhaps shifting colors after a while helped with that. Maybe it would be a good idea to change colors (and ad locations) every couple months. I'm not saying that we should shift things a lot, but just a bit to make people notice.