Continuing with our look at the factors that could or could not possibly lead to your credit card processing program becoming hacked and primed for fraud, we can extend the urge for cautionary measures to identifying possible criminals in-store. This doesn't mean judging by appearances, but rather by behavior that could be a tip off to a card thief's intentions.
A post on Small Business Trends mentions a few things that merchants can do (and train their store's staff to do) to recognize someone who has perhaps already stolen someone else's card and is trying to pass it off as their own. One example it gives is for clerks to only accept proper identification as proof that a person is who they say they are ( a "letter of authorization" claiming that this person is allowed to use a card not in their name, doesn't count). The way a shopper handles and stores their means of payment can also be a tell-tale sign, as can the physical condition of the card itself.
Other hints can come from the way the potential thief conducts him or herself. This doesn't just mean stereotypical shifty or nervous behavior, but other means of artificially conveying confidence and sidetracking the clerk on duty from this visitor's true intentions.
While your point of sale credit card processing system could come under attack for any number of reasons and in a variety of different ways, you can take steps to keep the chance of a breach low, both outside the register and in, and try to catch those who have already stolen someone's identity.