When Larry Osterman mentioned News Flash: Spaces are legal characters in both filenames and passwords, I was reminded of my own little experiment with passwords and spaces.
Over a decade ago, I tried using spaces in my password, and they were accepted, but I ran into a different problem: Brand name bias.
The password system accepted "Coke adds life" as my password, but it rejected "Pepsi the choice of a new generation". Why did the password system accept a Coke slogan but not a Pepsi one? Hint.