A few years ago when I ran a directory I would get submissions like this all of the time.
@Sami4u, anantshri is correct. Google's AdSense spider can determine a theme through the HTML title tag and page name. If you want to avoid public service ads for a new site, make sure that the title tags, meta tags and page names are focused on a theme. Although Google says that they do not use meta tags for ranking purposes, my testing indicates that the AdSense spider does use them.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin