Wow, I've forgotten that we have this option and can't even remember adding it wow.
Go to components\com_hotspots\views\hotspots\tmpl\default_hotspot.php line 91
<?php if(HotspotsHelperSettings::get('hotspot_detailpage', 1)): ?>
<span class="hs-toolbar-separator"></span>
<a href='{{ readmore }}' class="btn btn-link btn-mini">
<?php echo JText::_('COM_HOTSPOTS_READ_MORE'); ?>
</a>
<?php endif; ?>
change it to:
<?php if(HotspotsHelperSettings::get('hotspot_detailpage', 1)): ?>
{{#if readmore }}
<span class="hs-toolbar-separator"></span>
<a href='{{ readmore }}' class="btn btn-link btn-mini">
<?php echo JText::_('COM_HOTSPOTS_READ_MORE'); ?>
</a>
{{/if}}
<?php endif; ?>
And after that it should behave as expected.
Regards,
Daniel