User blog comment:Alchimous/The Curse of Span/@comment-4954747-20121214033425/@comment-4536066-20121214052246

It's this crap, which shows up when you copy and paste text straight out of another website (like runescape forums) or rich text programs (like MS Word). The text retains the CSS when you copy it by writing it into a container tag with style attributes mashed into it.