Imagine: You do your homework, buy a car for a great discount, and then a few months or even years later, the cops show up at your door and repo it. You did nothing wrong, but the car is stolen and they're taking it back. You receive no compensation for the loss of the car, and you have no transportation. You can file a claim with your insurance company, but you probably won't be reimbursed.

The scheme is complicated and involves forged VIN stickers and something called "VIN cloning." It starts when a thief steals a car and then finds a similar car and copies the VIN number from another car and puts it on the new car, making it look legit. Because there is little inter-state communication between DMVs, moving a car from one state to another makes it something close to the perfect crime.

The Today Show offers these tips to consumers:

• Be wary of someone who's offering a discount of 50% or more.
• Always pull a Carfax report before buying a car.
• Beware of anyone who wants all cash or is anxious to close quickly.

But even that might not help because the report can come back clean because the VIN number is lifted from another car. Worse, many of these stolen cars are traded into legitimate dealerships. Check out the video below from The Today Show for more.