It varies from state to state. In the case of residential properties, the seller must provide the buyer with a Real Estate Transfer Disclosure Statement, which specifies the existence and condition of all known physical attributes of the property.
Sellers are responsible for disclosing only information within their personal knowledge.
However, sellers must fill out the form in good faith. According to experts, sellers do not have to make such dislosures. The two basic contingencies in a purchase contract are financing and inspections. Some of them are code violations that should be fixed. Most sellers like to make all minor repairs before going on the market in order to seek a higher sales price.