This one threw me for a loop.
I was editing a WordPress theme (Subtle by Glued Ideas), and I kept getting a “»” in the page title of the browser:
header.php
<title><?php if ( is_single() ) { ?> <?php } ?> <?php wp_title(); ?></title>
Adding two single quotation marks in the parentheses of wp_title solved it:
header.php
<title<?php if ( is_single() ) { ?> <?php } ?> <strong><?php wp_title(”); ?></strong></title>
Don't know what is the original correct way, or if this is the correct way, but there ya go. :-)
Subject to peer review