Is there a piece of cheap validation hardware where you can plug in both ends of your cable and a little display will tell you what kind of cable it is and if it is legitimate?
Maybe just have something like the USB killer [1] to "sterilize" cables. Zap the cable with a high voltage/high energy pulse, beyond what normal on-die ESD protection could handle. A bunch of copper and plastic won't get damaged (unless you really get crazy and it arcs over and carbonizes or something), but it will probably burn out any covert semiconductors in the cable. It's hard to absorb high energy pulses in small packages.