I have been using ouroboros' script for a while now, and I find it very helpful. But I have noticed something strange - sometimes a thread will not get marked as read, and sometimes it won't get marked with a red dot after I have posted in it. In the latter case, it will not get marked with a green dot later either. I found out that this happens when the time given for the last post in the thread is a minute earlier than the time given in the thread list. This doesn't sound like a bug in the script, but rather a bug in the forums - the times given for the last post should be the same in and outside the thread. No big deal, it doesn't happen very often, but I just thought it was a bit weird.
Edit: A current example is Thread 39298
. Actually in this case the times are not just slightly off - the last post in the thread was supposedly written on March 5 at 17:38, but in the thread list it says March 6, 8:51. Maybe the last post was deleted. In any case, the thread doesn't get marked as read.