I have dark spots, (not too dark), on my ceiling in some of my rooms. I have white "popcorn" ceilings, and up by where the wall meets the ceiling I have darker , almost like dirt spots. At first I thought they were from the hot water heat registers and radiating up, but since I noticed some toward the middle of my ceiling also..I'm thinking, they are sections of my attic that don't have enough insulation layed down.
Is this a good assumptions??
and what would be my next course of action??
Without seeing them, it's hard to say. Could be a leak, could be mold, could be mold caused by a leak.
If there's no vapor barrier or there's no insulation in that area, it could be condensation wetting the area. Probably lots of other things.
One co-worker ended up removing 50# of wax and honey from a hive that ended up in the attic. The honey stained the ceiling. Could be something that died in the attic. You'd need to go up there and poke around.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013