What is a significant sign of immediate water damage during a home inspection?

Staining on ceilings or walls is a significant sign of immediate water damage during a home inspection because it typically indicates that there has been water intrusion, which could stem from roof leaks, plumbing failures, or condensation issues. These stains often suggest that moisture has penetrated the materials and may lead to further complications such as mold growth, structural damage, and deterioration of building materials if not addressed quickly.

In the context of a home inspection, these stains are often visible and can give inspectors a direct indication of how severe the water damage is, allowing them to assess the urgency for repairs or further investigation. The presence of stains also often has a stronger correlation with active or recent water issues compared to factors like excessive humidity, which may be present without indicating a specific source of damage.