This is a touchy subject. The question of what one does or does not have to disclose varies by state. It is wise to check with your state's real estate disclosure laws before you begin repairs. This will help you understand the areas where you may need to invest more financial resources for legal advice.
However, be aware that most mortgage companies require that a buyer's potential home go through a qualified inspection and appraisal process. Some programs such as FHA even have their own requirements. If your home does not pass inspection then you will likely not be able to sell your home to a traditional buyer using this type of financing. However, other types of buyers exist.