I had the same scam tried on me a few weeks ago on a WordPress project. Was an agricultural site and I even wrote them a quick statement of work to try and secure the job. What a waste of time! I don't take credit cards but instead use Freshbooks and their pay by Paypal option. It does require that my clients use their bank accounts but for $10,000 or less transactions it only costs 50 cents. Saves a compared to the 3% that credit card companies charge.