Adsense stop words trigger Public Service Ads which gives you nothing when someone clicked on it.
I have this problem with one of my blog post before because it has stop words in it. Even if the traffic is high, I get nothing and loses something (bandwidth). The traffic is huge because I was able to optimize it for a highly competitive keyword: naruto porn. (I simply make a blog post condemning it. LOL!)
Now, the problem is solved. What did I do? I used alternate ads. When Google doesn’t want to show their ads, you can configure them to show an alternate ad. And on my case, I used Widgetbucks as an alternate ad. Now, horny people searching for naruto porn has something to click when they come to my blog post. Hehehe.