Etaoin Shrdlu was a pharase which appeared in daily newspaers quite often in prehistoric times. I wonder if anyone here knows or remembers why it appeared. I think I first encountered it in about 1940-1944. Will post again if anyuone shows interest in archaic anomalies.
The Devil Inside:The internet is awesome. Etaoin Shrdlu disappeared by about 1965-1970. I did not think it could be googled, which I guess is the way you found the Wikopedia article. It was more than merely a custom of the linotype operators. Etaoin shrdlu happens to be the most efficient 12 letters you can typeset. That mechanical device had to finish a line once it started. If the operator knew he made a mistake, he typed etoain shrdlu to fill up the line, expecting it to be fixed later. Due to time constraints, such errors often got printed, especially in early editions printed for sports fans.