Of course, AdWords can be quite difficult. But if you are doing it right you can see positive ROI. I have been managing a few account which had trouble doing that. But it really depends on your strategy. Want to play safe? 1. Forget that broad match even exists. 2. Focus on long tail keywords only, this will drive enough conversions while costing you less money.
I am sure that AdWords works! and the reason we paused our campaigns is that I think it's better to spend time on writing articless because we don't have the time to put on AdWords. The worst thing is that I can't really outsource or contract someone to do it because they must know a lot about my niche.
