First off, there's a picture of what I'm talking about. You have to look closely but you can see the joists & every nail they used to put the drywall up. I didn't realize it until now when I was laying on the ground playing with my son. What would cause the joists to show through the drywall? Thanks in advance!
Is that an uninsulated or minimaly insulated cieling?. Cold cieling joists transmitting cold from an attic can cause condensation in small amounts on the surface. Dirt in the air likes to stick to damp surfaces.