If you pull up a forum subscriptions page and turn editing on, the forum renderer does not seem to be displaying rarrow and larrow correctly.
In /lib/outputcomponents.php the attribute function returns:
return ' ' . $name . '="' . s($value) . '"';
So the ampersand is being quoted. Removing s() - in other words:
return ' ' . $name . '="' . $value . '"';
shows the correct characters; however, Petr commented:
// no sloppy trimming here!
when he added the code: