I don't really know how to phrase this but i have spent a lot of time in the woods with people. I have been over a hunting club we have for 30 years. I have had people get off our property and not even realize it. What i am trying to say is most folks don't have much wood knowledge or directional sense. Purple paint or signs gives a directional line if it is an honest mistake. If they do it on purpose it still gives you a gotcha point when they start trying to lie their way out of it.