Comment on Ad Clerum WordPress AdSense Theme by SEO Dave.
Like you I’ve noticed a tendency for the home page of a new WordPress site or one with AdSense just added to have less relevant ads than deeper content on the same domain.
I’m not sure why that is, I’ve put it down to what the AdSense bot saw when the first AdSense ad was loaded on the home page for the first time. So if you installed WordPress and you get the Hello post mentioning WordPress, you are going to get WordPress ads. Add to this the Blogroll I mentioned before and it makes sense.
Look at your default About page to see what I mean. The bot has to spider a page just like GoogleAdbot (their AdSense search robot) and that takes time (it’s not instant). If you update your About page today the bot has to come back a respider/index it, in the meantime you’ll get Blog type ads.