Have anyone tried the Adsense preview tool (https://www.google.com/adsense/previewtool) ?? It looks good and works pretty well!! (it is only avaliable to Internet Explorer, but thats ok)
I like to use the tool on competitors websites who do not have adsense. Shows me what they would be displaying and maybe a few things I could change. It is a handy tool, although, it has kinda worn out its welcome with me. I cannot understand how it can serve information that quickly, I mean, isnt the mediabot supposed to crawl to ensure relevancy?
Maybe it's using data from the googlebot. (I don't even understand why they have two separate bots....)
You can change colors, target for a specific country and preview all these in your webpage! It's a very good tool!