Many people do so every week in church. My husband and I will soon put our house on the market. It is a beautiful house in a great neighborhood, but the builder cut some corners on the construction . . . My husband says to let the buyer's engineer determine what needs to be done, but I'm afraid he'll miss some things. I said that the seller should answer all questions honestly and should not conceal any flaws but that he need not volunteer every defect in the house.
Common practice makes it the buyer's responsibility to have a good engineer check out the place.
Alas, I was wrong on the law and lax on the ethics. But even if the law did not require such positive actions, ethics does. While there is a distinction between passive silence and active deceit, to withhold important facts about the house is hardly honorable. In the buyer's place, surely you would want a candid account of the property. The seller should tell all and accept a fair price.