I have just checked one of my sites (as it seems to be doing poorer than normal for Adsense today) and I found that the ads are not very well targeted to the content on the home page. A quick check on some of the article pages shows that they are well targeted but the home page is showing highly irrelevant ads. Usually they are very well targeted and I wonder if this happens to anyone else.
I don't think that will help as they are fine. I think Google is screwing up somewhere and if I changed anything it will make no difference.
I have had a lot of problems with google not targeting to the content on my sites. I had to change the content for the ads to update though.
I just added two new on-topic articles and still get highly irrelevant ads. If it stays like this I will getting in touch with Google as it is losing both of us money.