The failure of a seller to disclose a defect is not uncommon, and it is very difficult to prove prior knowledge. Since you became aware of the mold during the inspection process, provided for in the contract, and exercised your option to cancel the purchase agreement, you have no damages from the failure to disclose.

Most important, the mold was apparently concealed under carpeting(your description). How can you prove the homeowner was aware of it and failed to disclose it. Is it plausible he was unaware or its presence or unknowledgeable of mold? Dismissed, next case.