Can Adword help your Adsense income?

I saw some sites using AdWord to promote themselves and show Adsense on their sites to get paid. Does anyone know if this is economically possible? Because u need to pay google for AdWord, then get back some income from Adsense. It seems to me it is not a good way, but still some people are doing so. Just wondering if there is any tricks here.

 

Unless you have a very high CTR and a considerable CPC this wont be working for you.

 

this is called arbitrage and google doesn't like it anymore