Several reports are estimating between half a million and 1 million cars sustained flood damage due to Hurricane Harvey.

Many of those cars are still being sold, either through used car dealerships or through online classified ads, and sellers are reportedly attempting to disguise any signs of flood damage.

Advocates worry thousands of Houstonians who are looking to replace their flood-damaged cars may inadvertently purchase one potentially with the same or worse damage than they incurred during the storm.

Here’s what they say you should look out for to avoid purchasing a flood-damaged vehicle:

Check The VIN. When a policy holder registers their vehicle as a total loss due to flood damage, the insurance provider records the Vehicle Identification Number (VIN). Buyers can find a car’s VIN on the driver’s side dashboard or inside the driver’s side door. Services such as CarFax and VINCheck usually let users check a car’s VIN for insurance claims.

RELATED: Report: Hurricane Harvey Left Up To A Million Cars Destroyed, Damaged

Too Good To Be True? When a buyer sees a sale price they may feel too good to be true, the bargain-basement price can be a strong indicator of if the vehicle sustained flood damage. Ask the seller about the car’s history, especially if the car logged any time in Houston during the storm.

Trust Your Nose, Not Your Eyes. A car can appear to be in pristine condition, even coming with the coveted “new car smell,” but those appearances can be deceiving. If the seller insists on keeping the car’s windows down, or the interior smells strongly of scented products, these can be red flags indicating the presence of mold or mildew in the interior.

RELATED: Report: Houston New Car Sales Double After Harvey

Carpets Carry Clues. If a car’s carpet is discolored or recently replaced, these can be clues the car is coming with bigger issues than its interior finishing. Even if the carpet in the most visible areas appears unaffected, the carpeting in hidden areas, such as under the seats or in the corners, can still carry some moisture.

Good luck out there, Houston.