"Negative keywords can … refine your keyword list and filter out unwanted traffic for your paid-search campaigns," writes Jill Solomon in an article at MarketingProfs. "Excluding specific words or phrases that aren't relevant to your product or service can help you reach your ideal prospects, reduce your cost per click (CPC), and increase your return on investment."
Read post here
http://www.marketingprofs.com/short-articles/2317/how-identifying-negative-keywords-can-lower-costs-and-boost-results?adref=nlt062811