The dash is probably the single most abused piece of punctuation in the English language. No, I mean it.
Dash abuse. It’s a serious crime, with serious consequences. I’m guilty of it; you might be guilty of it. We spend years—lifetimes—figuring out when to use commas, colons, and semicolons. We learn to do nonsensical things like putting the comma inside the quotations because, well, that’s the way it’s done.
We spend a lot of time and energy getting grammar and punctuation right. But when we need a dash (whether of the em or en variety), a hyphen, or even a minus sign, eh. We just mash the one-size-fits-all “dash/hyphen/minus/whatever” button next to the zero key.
We might even get crazy and press it two or three times — like this — and we might squirt in a couple of spaces on either side, just to make it clear that we mean business. It’s what you could call a descriptivist, anything-goes approach to punctuation, and it means there are about a dozen ways to represent the following Einstein quote: