By default, JSF pages do allow comments, which is a real drag (http://stackoverflow.com/questions/3388109/how-can-i-remove-html-comments-in-my-facelets). It would be good to set the javax.faces.FACELETS_SKIP_COMMENTS property to true in the web.xml :

<context-param>
    <param-name>javax.faces.FACELETS_SKIP_COMMENTS</param-name>
    <param-value>true</param-value>
</context-param>