Question: I have a stain on my bathroom ceiling that is in the middle of the first floor of my house. The room above does not have any plumbing, and nothing has been spilled up there. What can cause a ...

Many stains are instantly noticeable. But while a wine stain on a light-colored carpet or a gravy stain on a white shirt tend to jump out right away, other stains sneak past our radars every day.

Q: I have a stain on my bathroom ceiling that is in the middle of the first floor of my house. The room above does not have any plumbing and nothing has been spilled up there. What can cause a problem ...