Not providing the buyer with legally required disclosures.
There is an important form used by REALTORS in California transaction named the Transfer Disclosure Statement (TDS) for residential sellers to make certain written disclosures about their property. This form is required by the California Civil Code, since 1987.
Sellers often forget how important it was to them as a buyer to find out what their seller could tell them about their new home. Buyers still want to know, so what is a checkbox and a few blank lines to fill in to a seller on the TDS is a world of important information to the buyer(s).
The TDS is meant for the seller to tell the buyer what is within their ordinary knowledge about their property, i.e., repairs, how recently painted, permitted and non-permitted modifications or additions, how old the roof is, new flooring, is there a sump pump under the subflooring--in other words, things that the mentally present person is not likely to have forgotten about. There is even an additional multi-page Property Questionnaire covering numerous topics to prompt the seller's memory, a document which is not legally required but is often requested by the buyer's agent. Buyers sometimes think that sellers purposely didn't tell them certain things, like that rot that was found after the brick facing was removed from the front of the house. But things can happen that the seller may have no knowledge of, especially if they lived there for many years without spending money on maintenance. But then there's the case of the freshly painted bathroom that may have been covering over the water stains from a roof leak, which the buyer found out about on physical inspection, but where there was no disclosure about it on the TDS. Sellers, it only upsets buyers when you're not totally forthcoming--it may be painful to negotiate during escrow and walk away with less money, but it could be saving you from an angry buyer (that did not discover a problem during escrow) and a lawsuit later on.
It's important to give this TDS document to the buyer, in the time period stated in the contract, since the buyer has the right to cancel the contract otherwise. If the seller thinks he/she doesn't have to provide this form and refuses to do so, the seller will be liable for any resulting damages (that means . . . attorneys, and more money spent). If they seller accidentally includes wrong information, and then realizes it later, they may amend the TDS and give it to the buyer. There are certain sellers exempt from this form, such as in probate cases, and trust, plus a few other types.
And there are other required disclosures, including those about natural hazards, lead paint, special districts, and others, such as death on the property. If someone died on the property more than 3 years prior to the buyer's offer to purchase, or if they died from AIDs, the seller is not required to disclose that fact, unless the buyer asks. If someone did die before that time, then the seller must disclose it--because if you the seller thinks the buyer won't be talking to the neighbors later on, you should think again. Buyers should know what they are concerned about before and during their buyer investigation period, so that they are not unpleasantly surprised after they move in.
This is a more complex and lengthy subject than in this post, if you have questions please feel free to contact me.
An observation: It's so very difficult to absorb all that is conveyed in the tiny print in these transactions, so my advice is: turn off your TV, do not check your phone, your iPad, your computer, just sit and focus in as quiet a place as possible when completing your documents. It is not a time for multi-tasking.