ScottM - 8:32 pm on Mar 1, 2013 (gmt 0)
I have a sure-fire way to tell when to clean my LCD screens:
When I want to make fun of someone (some web page) for improper/misplaced punctuation (a period or a comma) and I discover it is some dust or dirt or splashed liquid on MY screen that LOOKS like punctuation.
The worst time to have a dirty screen is when I'm using php and trying to find an error in a script. (Where an extra period can totally break a script.)