I skimmed through the list of existing threads and didn't see anything that jumped out as being this issue, but if this is a duplicate then I apologize.

The bold font used to indicate that a forum has new content is very similar to the default for those that do not - it really should be a much heavier bold, or a different color, to help differentiate. Attached is a screenshot showing the difference, and it's very hard (and probably almost impossible on higher resolutions, or lower quality displays where there might be color shift) to tell the difference at a quick glance.

 

In the meanwhile perhaps a temp fix of something like this?

Code:

  .node.node .forumNodeInfo.unread .nodeIcon::after, .node.node .categoryForumNodeInfo.unread .nodeIcon::after {
    color: #BAD6C2;
    text-shadow: none;
  }

 
  .node.node .forumNodeInfo .nodeIcon::after, .node.node .categoryForumNodeInfo .nodeIcon::after {
    color: #354436;
    text-shadow: none;
  }