I made a plugin for my blog that replicates the
backticks function available here on the forum. It's a simple little plugin. As you can guess it uses
htmlspecialchars() (among other things) on the stuff in the backticks. But I found something weird.
If a comment contains
&#39; in it, it doesn't post. (Incidentally, I'm having trouble pasting it here, but you can probably tell what I mean--remove the "amp;" from the entity.) You hit submit, and WP just reloads the current post without posting the comment. (It's not in the moderation/spam queues, it's just gone.)
EDIT: It took me a few tries to get the entity to paste. It's there now.