Id say use it. Your telling me that if someone put a ladder stand up 15 years ago on public land than he should have that area for the rest of his life as long as he isn't sitting there? He might as well buy 6 ladder stands, set them up 50 yards from each other and have a whole area for the rest of his life until the stands rot away. If there is a stand there and no one is in it, I say go ahead and use it. The stand could have been put up 6 months ago and the guy only uses it once a month. If he comes to use it, kindly get down and try another spot. Its PUBLIC land! In college there were four stands I passed every day of gun season (10 days long) and not once did I see anyone in any of them.