Do People Know When Car Dealerships Have Hugh Discount Sales It Can Be A Ripoff?

I bought a car during a weekend only sale. 3k off the sales price. I use a credit card and they financed the rest. The amount I put down on credit card was the over amount they charged. I did not know it till I got home and did a kelly book check. Turns out the car was a manufacture mellon that was only 2 years old. It was nearly perfect but it had a air-condition leak that cased a hugh mold problem. They put the car on the lot with out dealer papers and say it was just traded in by an earlier customer. It still needed to be safe inspected and they would remove the stale smell at that time.
I was charged 22,000 dollars with interest on a Volkswagenn Passatt with only 52000 miles. They worked on it 2 times for the smell. The only way is to completetly remove all the interior carpet, seats, and cloth material. They disguised the smell with some spray which after one day returned so bad we had to have all the windows down just to breath. I ended bringing it back and paid 2 thousand dollars to get my old car back. I would have lost 8 thousand if i hadn’t. The kelly blue book is only 14k on a car in mint shape with same mileage. Also the car fact site showed the car had been in an accident and was sold in auction 6 months prior and no other sale.
The dealors use these mailings to force people to buy without knowing what is wrong. They say the car will sell with the next customer because of the 3k deal they offer with the mailing. Also the new electronics are soo bad they constantly are in the shop. Its a hugh scam!!!! The only way to buy one is to have a lap top computer that can get online at the dealorship at the time you look at the car. They move the cars to the next dealership so its not there after you have gone home to check the carfax.