I have been working with Google Keywords on and off for 3 years now. I have seen their system evolve and change a lot during that time, but one thing has stayed the same: the need for negative keyword research just as much as keyword buying research.
I am appaled when I see client campaigns getting .25% click through rates because they haven’t properly targeted how their ads are served, either by including them in the (crap) content network, or by not researching and including negative keywords. This is bad because it makes google look innefective, when its not. Its the person running the campaign that’s innefective.
A good Google keyword ad group that has the right creative, is targeted well, and has negative keywords and fresh ad copy should get between 1% and 3% CTR (click through rate) on average. And some words with your brand name terms will do even better.
So the lesson here is, get your keywords out of the pornography searches, out of the (crap) content network and dump your keyword manager if they didn’t do it to begin with.