The old adatage of "buyer beware" does not apply to residential real estate in California. Under common law--that being law that has been formed by case law and not codified in a statute--a seller has always had the duty to disclose to a buyer all material facts that might affect a buyer's descision to buy a home and at what price.
In 1987, the California legislature codified this legal principle in Civil Code Section 1102.6. In that code section, you will find a form that is now required in most residential sales. The form includes a check list of areas that must be affirmatively disclosed to a buyer. The form also requires that the real estate sales people involved in the sale of the home must also make an inspection and disclosure.
It is no longer "buyer beware"; it is really "sellers and agents beware". The seller must disclose all material facts actually known about the home and the agents must make a reasonably diligent inspection of the home and also declare all material facts known to them.