We are learning from Case Studies in Business Ethics by the late Rabbi Dr. Aaron Levine z"l professor of economics at Yeshiva University.
Question: is capitalizing on an informational advantage that one has over another person immoral?
Halachah's disclosure obligation is geared towards the expectations of a hypothetical reasonable person in that position. What constitutes reasonable expectations will depend on the type of transaction that is being conducted. In a face to face transaction the seller is not responsible to point out to the buyer the visibly obvious defects in a product. The reasonable expectation is that the buyer will see the flaws without the seller having to specifically point them out to him.
Hence, voiding or adjusting the terms of a concluded transaction on the basis of visibly obvious flaws is not entertained by a Jewish court.