Understand that Adsense Ads are personalized based on a lot of factors.
Currently on my screen:
-Adsense Publisher
-Adsense formats
-Adsense ADS
-Sample Proposal
Are you reading a forum post about Adsense at the moment? Yes. The content of the page you are looking at is one of the determining factors for which ads are displayed.
Adsense is clueless on here. Mine currently has:
-Dow Stock Market
-Stock Shares
-Stock Price
-How to Buy Stock
Does this site discuss trading and markets? Yes. Ads delivered therefore match the content.
Do you ever visit sites that discuss stocks, the stock markets, finance? Your browsing history is another determining factor in which ads are displayed.