Hurricane Harvey is still wreaking havoc and destruction on Houston, Texas, and the surrounding areas as of this writing. And now we're learning from CNBC that an estimated 500,000 vehicles will be declared totaled by the time the storm passes. Flood damage is the reason for these vehicles being sent to the scrap yards but, unfortunately, not all of them will be – and this is where used car buyers need to be extremely careful.

ABC Action News out of Tampa Bay, Florida, has learned that an estimated half of those vehicles, around 250,000 in all, could end up being sold as used cars without the legally required flood label. Why? Because some shady used car dealers know exactly how to clean these flooded vehicles up just enough so that they can pass with no indication of flooding. It takes only a few hours of cosmetic work to make everything look new. Flooding causes cars to literally rot from the inside out, and affects all mechanical, electrical and safety systems. Unsuspecting buyers will simply have no idea about these cars' histories. Furthermore, Houston area residents will begin filing insurance claims and receive payouts to buy new cars.

It'd be a sad and cruel case of irony if they purchase a car with hidden flood damage. But they aren't the only people who could be fooled; it's possible (and likely) these cars will be sent out of state as well. So here's what you need to know, according to Carfax, in order to identify a potentially flood damaged car: Upholstery does not match the carpet, rust on door hinges, seat belts or inside bolts damaged, musty odor, and water lines in the engine and/or trunk. Of course, you can also simply get a free Carfax report. State laws do require any cars for sale that were in a flooded area to have a title placed in a visible location indicating as such. Still, buyers need to be on the lookout for these appalling sales practices in the coming weeks and months.