I was at LACMA a few years ago and noticed that they started putting laser range-finders in front of most things that would shriek if you got too close. I thought: well, that's the End Of The World for sure.
Then in the next room I saw some idiot absent-mindedly put his finger on a de Kooning and trace a line that ole Willem had made with a brush. The oil he left that day on the piece will be visible in ~20 years and will likely need to be restored in 50.
/jordan