If you are outside of the US area and you want to view AdSense ads as if you were a US user, there are ways you can do it. One way is to go through a US proxy of some sort, but that can be hard for some people. A thread named How Can I See AdSense Ads On My Site As If I Were In Another Country? shares a response from Jenstar.
Use the AdSense preview tool, it allows you to geotarget to many different countries to see up to 12 ads for each geolocation. You can also click on any of the ads to see the landing page without costing the advertiser any money (or getting yourself suspended from AdSense).
So there you have it. Forum discussion at Search Engine Watch Forums.