Why would people need to spray way markers in Caplecleugh? It isn't exactly complicated.
If folk feel that they need to spray arrows, then perhaps they shouldn't be in there in the first place...
More to the point, how easy are they to remove?
I'd be keen to get them shifted.
They spray them for the same reason that they do it within sight of daylight.
Remove with a wire brush and spray a mouthful of cheap supermarket bitter lemon that reacts slightly with the limestone. I discovered this accidentally in Smallcleaugh when I had an arrow removing orgy.
People like this are in truth a blasted nuisance.
Now wouldn't it be funny if they went back to their cars and found some helpful person had sprayed forward pointing arrows on them indicating the direction they should be driven. Just so that they know and dont make the easy mistake of driving back down the M6 in reverse.
My avatar is a poor likeness.