What is this stain drippage on my interior wall?!?

So I've noticed these weird looking drips that aren't wet or anything it just looks like some kind of dirty or brownish dripping stain on the drywall. Ive just noticed it today since we lived here since this past January. The runs are not wet just looks like ...I don't know, like old syrup lol. Way up this high I doubt anything was squirted up there. Nothing was ever hanging on this wall either. Zoom in on the pics below. Check it out. Thanks

 

Moisture in the air will deposit dirt on the wall, I can't see it in the pictures but it sounds like a smoker in the house.

 

Hmmm interesting