I know that some people go and sign up for adwords, sign up for adsense, make their own ad appear, click it, see how much they were charged. They then believe that Google is ripping them off (as for example they may recieve $x via adsense, but had to pay $x+y on adwords). Of course Google takes a cut. But the important thought I am trying to tell you is that remember that on the actual search results advertisers pay a lot more to display ads (or pay for the clicks anyway) than they do for the content network (Adsense).

Hope that made sense. More small posts coming soon