Criminal Sentence 82: Hyphens or Em Dashes

A reader, Eric, has a question about em dashes:
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This sentence is from this article published today on Politico.com.

When Politico reporters working on a story about Obama's law review presidency earlier this year asked if he had written for the review, a spokesman responded accurately - but narrowly - that "as the president of the Law Review, Obama didn't write articles, he edited and reviewed them."

What I'm wondering about is the use of the hyphens (rather than dashes) to offset the phrase "but narrowly."
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Eric is right that you shouldn't substitute hyphens for em dashes, but it is a fairly common sight. These particular hyphens have spaces around them, so they are not confusing. Sometimes, though, I see hyphens instead of em dashes but with no spaces, and it can get confusing. Here's an example of a confusing sentence:

I saw a lion-eating a banana!-at the zoo.

Since a hyphen links words together, this first hyphen seems to link "lion" and "eating."

If you must use hyphens instead of em dashes (not recommended but sometimes unavoidable since the keyboard doesn't have an em dash key), please double them up (as in --) or put spaces around them. In Word you can set the program to create an em dash when you type two hyphens.

If you'd like to review what I said about em dashes, see CS 56.

Thanks for your question, Eric.