Oops, who is the biggest liers in the world? Car dealer and lawyer!!!
Never trust what they say. I tell you my experience. I bought one supposed very good used car (> $10000) several years ago from the same big dealer I bought a new car before (So I knew him). At that time he promised the car was good and clean and blah blah.... But you know what? When I tried to insure that car, the insurance company checked the record and told me that car had big accident before. Damn! Once the contract is signed, every dealer is not as friendly as he/she was. Of course you can ask help from government agency about it, but normally it's difficult for them to punish dealer because you don't have hard evidence like voice records etc... The final result was I traded in the used car for new one, but much less value (>$1000).
Got several similar kinds of strories from other people too.