Yep, I picked up a trick while backpackign across Asia for this. My signture is upside down on my card. So if I refute any claim that appears I can point out the fact and show at what point the transactions started.

I travell alot and I've had my gear stolen a few times, and atleast once a year (usually a month after I get back) I have to go through claims processes to remove charges which start appearing. Total pain, and why I'm suspicious of another system that looks atleast as bad as whats already out there.