XSLT hide element IF string is empty

Is the text in an element called imageText or is it in a variable called $bottomImageLeftText? It seems like the latter, so please try this:

<td width="300" height="114" valign="top">
  <xsl:if test="$bottomImageLeftText != ''">
    <div class="imageTitle">
      <xsl:call-template name="getText">
        <xsl:with-param name="imageText" select="$bottomImageLeftText" />
      </xsl:call-template>   
    </div>
  </xsl:if>
</td>

You need to condition on the value you would be passing to the with-param, not the parameter name (which is only meaningful inside the called template). So wrap the div element in a

<xsl:if test="string($bottomImageLeftText)">

This will include the div and its contents if the string value of $bottomImageLeftText is non-empty - which includes the case where it contains only whitespace. If you want to treat whitespace-only the same as completely empty you can use

<xsl:if test="normalize-space($bottomImageLeftText)">

I would try something like this:

<!-- Code which calls the getText template and passes the bottomImageLeftText variable -->
<xsl:call-template name="getText">
  <xsl:with-param name="imageText" select="$bottomImageLeftText" />
</xsl:call-template>

<!-- getText template which checks the param imageText for an empty string. -->
  <xsl:template name="getText" >
    <xsl:param name="imageText" />

    <xsl:if test="$imageText" >
      <div class="imageTitle">
        <!-- your code, display image title -->
      </div>
      </xsl:if>
  </xsl:template>