The number one sign that you may be experiencing click fraud is that your pay-per-click campaign costs are continuing to rise while your online sales are not meeting expectations. Sometimes if a keyword is too broad you may also experience this. If your cost per click is really sky rocketing then you are most likely experiencing click fraud. Click fraud usually happens to people who are in a number one position or who are competing for a highly contested keyword.

The number two sign of possible click fraud is that your conversion rate for paid searches are lower than the conversion rate of your free listings. Somebody probably wants you out of the way as far as competition goes. If your keywords are the same for free listings and paid listings your conversion rate should be almost the same.

The third sign of click fraud is that the cost-per-click for each of your best performing search terms have been steadily increasing. If you are paying more and the performance of the best search terms are plumeting then this is most likely click fraud.

The fourth sign is that you suspect your competitors are deliberately driving up your costs by generating fraudulant clicks. The internet is a competitive market and I don't think people should be accused of click fraud without reason. Unfortunately there are dishonest people out there.

The last reason is that you do not have a tool in place that is specifically designed to catch click fraud. Tools may help, but knowledge will be more helpful. One way to avoid click fraud is to not compete for the number one position of keywords, especially highly contested keywords. Be careful and knowledgeable. Every click counts.