One big problem about curly quotes is that many default Windows fonts have their curly quotes all mixed up – Verdana is one of the offenders – as you can “see here” on HN. I then just refuse to use such shoddy fonts. Not the curly quote’s fault that the font is screwed up. (You can use incorrect UTF-8 characters to get the correct curly quotes when using something like Verdana, but as soon as your text is copied and the font is changed you again end up with the wrong curly quotes.)