HTML character-entity escaping is sub-optimal.
I was very surprised to see my post look normal in the editor, but appear in the timeline as
\"Mastery is the experience of possessing%u2014or being possessed by%u2014a deep understanding of a subject [....]\"
It was an except from http://nielsenhayden.com/makinglight/archives/014027.html (4th paragraph), also copied below, with quotation marks added as in my post.
"Mastery is the experience of possessing—or being possessed by—a deep understanding of a subject"
I can almost understand the em-dashes being converted, although silent conversion is still annoying.
But dumb-quotes entered directly through the editor?