Darkened Spots on the ceiling
 

I have darkened spots on my ceilings, You can also see darkened lines like they run under the joists and onto the ceiling below. We had all the ceilings painted around 4 years ago - this doesn't look right. What is it ? Could it be an attic ventilation issue. The insulation running to far between the joists to the soffit thereby blocking the soffit vents.

Yep watch out big time for mold. My best friend is paying a huge bill for the cleaning of his house after something in his bathroom leaked into the walls and mold spread. Was like 4 or 5k