Two blogs, created on the same day, on two brand new domain names with no history or prior traffic.
No incoming links other than Technorati thus far.
One has Adsense on it, the other doesnt
15 posts on each three days later, and I checked Google.
The blog without Adsense was completely spidered and in the results. Every single post was there. The blog with Adsense had only the index page in the results.
Granted, it’s too small a sample to be significant, and it might just be a fluke, but I find it interesting nonetheless.
It wouldn’t surprise me if Google would penalize sites that, when they are spidered for the very first time, show Adsense. That would be a great way to catch made for Adsense (MFA) sites, since they have Adsense from the get-go, while “real” sites will focus on content first and monetization later.