Whatever your adsense stats are in terms of CPC and CTR, the easiest way to gest the very best of adsense is to:
- display only the most paying ad (they are ordered by highest eCPM (combination of CTR and CPC) so show only the first one in a single ad block)
- optimize CTR
That way, on your specific topic, you'll see how adsense performs at the best conditions possible, only the most paying ad at a very well located spot.
I'm doing that on a site I'm building now, but since I do a adsense revenue sharing system, I'll display 3 ads, each with a block size of 234x60 which displays only one text ad at a time (no graphic/video ads for this format)
So my main issue is how to get the best possible CTR for those 3 small ads. Of course I put them above the page fold and I carefully choose their color to match the site's theme at best. They should really not be able to be missed from anybody visiting the page. Then up to them visitors to click on the ads or not, but at least they should notice the 3 ads and not immediatly take them for ads either.
If the CTR is not too low, the eCPM will be at its best possible for adsense, because the CPC will already be the best I could get for this site (except for the graphic/video ads)