Yes, they are required to disclose. Even "as is" sales require disclosures if the owner is aware of problems. Keep in mind that what you might consider a problem might not be something they consider a problem (like noisy neighbors who ruin your quality of life...you'd want to know that, but you'll have a hard time finding someone to disclose that). Most disclosures are related to structual defects, problems such as termites or water damage, dry rot, roof leaks, bad plumbing, not up to code electrical, etc. Make sure you have the house thorougly inspected, make sure there was not been any unpermitted repairs/modifications done to the home.