Good Faith when used in association with the sale of real estate indicates that the seller has made due diligence to disclose any past history, faults, defects or foreseeable problems that a buyer may have with the purchase.
The Business Dictionary.com's definition of good faith is; Effort made, information given, or transaction done, honestly and without a deliberate intention to defraud the other party. However, good-faith does not necessarily mean 'without negligence.' Also called bona fides, it is implied by law into commercial contracts.

Source:
http://www.businessdictionary.com/