It could be an obsessive compulsive trait or ... ah... who am I kidding.  I'm OCD and I have this need to clear the screen of anything that isn't part of my current process.  In Windows, the command is CLS, in Linux, the command is clear.  Pretty basic commands but in Linux there's a slightly fancier version which allows you to clear the line while in the midst of typing out a command by simultaneously pressing:

Ctrl L

Simple but helpful when you're in the middle of a long string.