virtually all of my interior wall have dark spots where i believe the screws?or nail heads are. no protruding nail heads...just a round dark area from ceiling to floor. how do i get rid of these? it is very ugly and it seems like i can wipe the marks off but they reapear.

I'd set them if they are nails or screw them in further if they are screws. Then apply some dry wall, sand and repaint.

I'm not an expert like some of the people here but that is what I would do. Try a few first to see if it solve the problem.

I heard about something like this in a contractors class. People were experienceing this "ghosting" where the studs were colder than the insullated part of the wall and the air moisture would condense on them and catch dirt in the air. Soon all the studs on the exterior walls were visible by the extra dirt. They didn't have a great solution after the walls were constructed however. Sorry! Hope this helps explain the phenomenon. Could the drywall nails/screws be getting cold enough to do this? Or maybe they are rusting thru?