From time to time all of our credit cards expire. Some of us store our credit cards on various websites in order to make the check-out process easier; there will come a time when one or more of us will attempt to make a purchase on an opaque travel site forgetting that the card we have stored in said website has expired....surely this is just forgetfulness and not any sort of fraud.
In the context of what was proposed in this thread, I think your (true) observation, djs, rings rather hollow. There's a difference between accidentally using an expired card, and using an expired card on purpose, repeatedly, knowing full well that it's expired, and feigning innocence in the hopes of gaining information to profit on Priceline. It's similar to the difference between accidentally crashing your automobile & receiving insurance payment, and staging an accident so that someone else's insurance pays out for a car you don't want, or injuries or obligations you don't really have. Truly, it can be difficult for an outsider observer to always know the motives, but HABITS will tell.