I’m remodeling a bathroom at a customers house and noticed that there were signs of long-term water damage on the ceiling below. I needed to access the p-trap for bathroom’s tub, which gave me the opportunity to fix the damaged ceiling. When I cut out the drywall it was clear that the dripping was very long standing as there was clear evidence of significant water damage. See photos below.

This is the ceiling below my client’s bathtub.
I cut out the ceiling to access the p-trap.
You can see how significantly the old drywall was damaged.