If you want to see the RAW xml returned by the Refinement Panel web part then replace the existing XSL with the following (do remember to backup the original):
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:template match="/">
<xmp><xsl:copy-of select="*"/></xmp>
</xsl:template>
</xsl:stylesheet>