Yes, certainly. I own one that has been painted black, with a finely ground coal and oil mixture and can show someone another, much larger, one that has been painted with burnt ochre along one face. I don't think they were painted all over - like a car is sprayed - but were highlighted. The practise was continued in the North Pennines up until the 1960's by decorating the north-facing sides of drystone walls with a burnt ochre wash. Just the faces were painted and the caps (copes) and throughs were left plain. I can show many examples of this but have seen no academic account. There's even a railway bridge on the south tyne line that still has traces of red on its northern side. So the answer is - yes, certainly. It's mainly all washed off now.