I agree. A sign should read be considerate to other visitors and the environment, but this is stating the obvious. Why would a new sign get any more respect than the current one that asks visitors to take their litter out with them? For those that already do so you would be preaching to the choir, and for those that don't a sign would not make any difference. Furthermore, what if someone else then put a no nudity sign up? No sign and a tolerant but respectfull attitude for all visitors is better in my opinion.