I believe that paid advertising online is as relevant as paid advertising offline. Having said that, is obvious that if you place a small ad in the corner of a golf magazine, and your product is a Tattoo Shop, then you have thrown your money away. Same applies on the internet. Determining your target market is key in driving a positive ROI campaign, yet so many businesses out there (including myself) go without.
Before throwing the towel and trashing Adwords, try first to find your right audience and attack it with all you have.