Which of the following scenarios would be categorized as a material defect?

A material defect in real estate refers to a significant issue that affects the value of the property or poses a risk to the health and safety of the occupants. When considering the provided scenarios, the situation where the roof has leaked in the past is a clear example of a material defect. A leaking roof can lead to further damage, such as structural issues, mold growth, and water damage to the interior of the home. This not only affects the integrity and longevity of the property but can also result in costly repairs, making it a crucial factor for potential buyers.

In contrast, the history of ghost sightings is more of an anecdotal concern and does not have a direct impact on the physical condition of the property; it is not something that materially affects its value. A malfunctioning dishwasher, while inconvenient, is considered a minor issue compared to a major structural defect like a leaking roof. Lastly, the sellers going through a divorce relates to personal circumstances that do not bear any physical or monetary implications on the property itself. Therefore, identifying the roof's past leak as a material defect is justified, as it represents a significant issue that cannot be overlooked in a real estate transaction.