This is a mistake that anyone using adwords and adsense should avoid.
I found a site who was created just to place google ads on it. This site targets some of the most expensive keywords like mesothelioma.
For what I could see, the site owner has both an adsense account and an adwords account. The big mistake he does is that he advertises on adwords for mesothelioma and doesn't have configured his own ads to not show on his site.
Here's a snapshot that I took from the site: