Speaking of signs, and their effectiveness, here's a sign from Whitney! It addresses a different hazard, and it is pretty uncompromising in its language. And yet how many times do we read about people continuing on to the summit, despite dark clouds in the vicinity and the presence of thunder? Though I wouldn't advocate removing the sign ... if it helps a few people to make better decisions, that is some good accomplished.
I don't really think signs on the trail or at the trailhead are particularly effective as to issues that seem remote at the time that they are read (as distinct from signs that warn of an immediate, concrete, danger, like "WARNING: MAN-EATING MOUNTAIN LION AHEAD 10 FEET ON THE RIGHT!"). Notwithstanding signs about altitude sickness on Kili, I saw even more stupdity on Kili than I usually do on Whitney (perhaps because of the great investment required to get there). And that's not counting the the doctor with asthma and an active cough who dexamathasoned himself up to the summit over the course of 8 days ... a doctor who I otherwise found to be wise, kind, and generous with his knowledge.
