How do you win as a marketer fighting pay per click fraud?

The spending for online marketing continue to grow. However, the ROI of this spending is now severely threatened by a recent challenge on the internet: pay per click fraud. Here are scammers, competitors or affiliates unauthorized use of trademarks in ad text online. Also be used as a brand keywords for visitors to send to websites that offer competing products or keywords are placed in links to illegal sites that sell counterfeit products.