Custom Template for Comment based on node type
According to Drupal 7 Template Suggestions, the custom comment template for a content type should be named comment--[node-type].tpl.php. That is confusing, because the actual template you have to use for an article content type is comment--node-article.tpl.php.

Alternatively you could add your custom template suggestion inside template.php:

function bartik_preprocess_comment(&amp;variables) {
  // Let's say you want to have a custom template like comment--custom-TYPE.tpl.php
  // e.g. for an article content type, the template file will be comment--custom-article.tpl.php
  $variables['theme_hook_suggestion'][] = 'comment__custom_' . $variables['node']-&gt;type;
}