The carpeted panel beneath the rear window in my 84SD is saturated with black soot. How does all the soot get into the diesel w126s?

I also have a few small spots of ruse residue on the headliner. Though tiny they will stick out like a sore thumb when I've installed all the fresh painted vinyl and plastic in this car. What's the quick fix for this, paint, whiteout, repaint the entire headliner?

__________________
84 300SD
85 380SE
83 528e
95 318ic