GUEST, KB, probably when you first went to the main forum page, the thread had had spam added which refreshed it, but by the time you clicked on it, the spam had been removed. Then if you went back to the main forum page using the back button, that would mean that main page still wasn't refreshed, but when you clicked on the thread again, of course it still showed up the way you saw it the first time.

I'll bet if you had refreshed the main page at any stage instead of using the back button, the thread would have been gone. Just a matter of timing. The clones don't leave the spam there very long.