There is a plugin called "All in one adsense and ypn" which lets you quickly integrate adsense and yahoo partner ads in your wordpress posts.
However, there is a catch, an option to donate % of earnings to the makers of the plugin. Even if you disable it or set it to 0%, some percentage of your earnings will go in their adsense account.
How did I find this out?
I searched the .php file of the plugin for adsense account and channel info and found a foreign channel and adsense id. I changed the adsense id to mine and changed the channel to my "test" channel, which was created specifically for the purpose of seeing if the plugin is stealing my earnings.
I let it stay for a few days and what a surprise! The "test" channel was generating income and views. This confirms my suspicion! The plugin will steal your earnings even if it is set to 0%.
Either change the adsense id with your own or don't use the plugin altogether!