I'm sure the idea's been around for even longer than that, though. I bet Benjamin Franklin (a publisher, among other things) must've had a choice quote about that...
1 Thessalonians 5:22 King James Bible
I'm sure if you dug around in Buddhist or Confucianist writings you'd find something similar. Being mindful of how your actions look is very useful in avoiding trouble.
It's happened before. Look at how society has evolved on questions of politicians' drug use, for instance. In 1970 admitting to have ever used marijuana would have been an instant career killer for a politician. By 1992 Bill Clinton could admit having used it, as long as he hedged the admission with a bunch of caveats -- he didn't inhale, etc. And by 2008 Barack Obama could openly admit having smoked pot regularly without any negative repercussions, as long as it was only in his wayward youth.
This is nothing new. When I was studying political science in the early '90s it was called "the Washington Post Rule": a canny politician should never put anything in writing unless he would be comfortable seeing it on the front page of the Washington Post.
(Why the Post? Woodward and Bernstein: http://en.wikipedia.org/wiki/All_the_President%27s_Men I have to believe the rule goes back even further than that, but presumably before their time it was called something else.)