Personally I think it would be too time consuming. For me, soccer suffers from a large degree of petty "cheating" that is seen as part of the game. It is so clear that, before the spray, defensive walls were routinely suffling forward. The referee could easily see that happening. So why not just penalise the offending behaviour by awarding a new free kick where the wall is (and a penalty if that is inside the box) or dishing out a yellow card, rather than faff about with a spray can.
I would take a very similar line with other petty crimes in football including, but not limited to swearing, shirt pulling, diving, time wasting and stealing yards at lineouts.
Soccer has a problem in that the majority of players breaks these minor rules most of the time. Strict enforcement would end that.