Since we seem to have @codinghorror’s attention today, here is a bug I’ve seen often:
Using the backslash character to, e.g. prevent © from appearing as © doesn’t work consistently. You can see that in the immediately previous sentence – there IS a backslash before the left parenthesis in the first © and this one too. In my experiments with this, it works thoroughly inconsistently, as far as I can tell. Putting backslash before both parentheses as in © sometimes fixes it, but not always. The only rule I can see is that having © more than once in one paragraph seems to affect how any other instances of © or ® or any of the others appear in the same paragraph.
I suspect this happens because the JS code doesn’t parse a paragraph of text in character-by-character left-to-right order, but instead probably does some kind of pattern-matching on the entire text at once.
(No, Discourse, my topic is not similar to “Are there any Roman amphitheatres that have seen constant use?”)