This should be a relatively simple solution but my mind ain't quite
working right today and google isn't being good to me.

I'm looking to test if any elements of a certain type do NOT have an
attribute with a specific value in an entire xml doc. For instance.

<!-- Pseudo xsl -->
<xsl:template match="/">
<xsl:if test="<!-- if all the foo elements in the doc only contain the
attribute att with a value of hi, don't output -->">
  <xsl:apply-templates/>
</xsl:if>
</xsl:template>