Seemingly random  being added into views node header for content type
&lt;h3&gt; in the views-view-unformatted.tpl.php is outputted only if you use Grouping setting in your view. So commenting that out is a bad idea.

Looking at your markup I can say with confidence that h3 is produced by either one of the following templates: 


node.tpl.php
node--news_story.tpl.php
node--product.tpl.php


Good point was made by rhuffstedtler, about checking which template is producing the markup.

find settings.php file and uncomment the line (usually last line) that says:

$conf['theme_debug'] = TRUE;.

Then refresh your page and check the source HTML code. You'll figure out from there which template you should be modifying.