If you have what looks like ISO-8859-1, but it includes "smart quotes" courtesy of Microsoft software, or people cutting and pasting content from Microsoft software, then what you're actually dealing with is probably Windows-1252. Try this:
<?php
$cleanText = mb_convert_encoding($text, 'UTF-8', 'Windows-1252');
?>
The annoying part is that the auto detection (ie: the mb_detect_encoding function) will often think Windows-1252 is ISO-8859-1. Close, but no cigar. This is critical if you're then trying to do unserialize on the resulting text, because the byte count of the string needs to be perfect.
