The very fact that a wallet.dat might be offered for sale, or, "help me unlock it and I'll pay you BTCBTCBTC" might in itself be a big neon light that the wallet.dat is either fake, or has been forged.
Agree. But still there is a extremely small chance to get a real wallet.dat. Or to help a person who forget the password.
Ex here:
https://bitcointalk.org/index.php?topic=5322325.msg56514279#msg56514279