I've had similar experiences with AdWords. It's very tough to get a decent ROI. Plus, toying with it is a real time sink, and if you want to do it scientificall

I've had similar experiences with AdWords. It's very tough to get a decent ROI. Plus, toying with it is a real time sink, and if you want to do it scientifically, then that's even more time and effort you have to invest.