Ok. When a thread a member has posted in receives a new post or posts, from somebody else, the thread icon is colored orange, and has a white ! within it. This is accompanied by an indication of how many new posts have been made. So, right now, in the mod thread of all places, I cannot get rid of the orange icon, and it says there are 2 new posts, no matter how many times I've tried to go to those new posts. ALSO, if those post do indeed exist, I can't seem to see them, with the most recent one visible to me being Permalite's response to Rol, where he says to "smash the report button".
The Hot Topics page shows who last posted in a thread, so the error here is that a spambot posted twice in the Moderator Thread and the anti-spam measures make the posts of a spambot invisible when the bot gets permabanned. Since the posts can't be viewed, the orange icon for unseen posts remains.
A simple circumvention to this problem should be to post in the thread yourself to make the most recent post in the thread one that isn't invisible, so the orange icon should go away.