He means that he could quite easily use the code
Code:
<script type="text/javascript" src="http://urlrate.com/embed/google.com "></script><br /><a href="http://urlrate.com/">yourname.com rated by URLRate.com</a>
And it would show a very high score for maybe a site that is not worth a score that high. However this could be avoided by just including the site name on the image.