Somewhere in the code, FR seems to be forcing “Unicode (UTF-8)” character encoding, but those apostrophes, smart-quotes, etc, are encoded with “Western (ISO-8859-1)” and the browser throws a placeholder for every character it can’t read.
If you force Western [Firefox: “View | Character Encoding | Western (ISO-8859-1)] the problem goes away, but for some reason, it is sometimes getting forced back to UTF.
Since you’ve pinged John, I see posts time-stamped in PDT, when I’ve selected Central time.