After initially solving my database character encoding problems by ignoring the specific strings in the wp-config.php file, I was finally forced to alter the characters in the database during a recent reshuffle. Whilst there are two automated solutions available via plugin, namely g30rg3x‘s UTF-8 Database Converter and the Modified UTF8 Sanitize Plugin, sadly neither worked in my particular instance, and indeed the former is no longer supported for current versions of WordPress, though reports on the WordPress support forum suggest there should be no issues.
Fortunately, an excellent guide was available on Alex King’s blog. For more information and follow-up comments, you should definitely read the full post, but here’s a summary of the method that worked for me.