What happens if you remove all irrelevant patches from a catalog and then update the catalog? Will the only irrelevant patches to re-appear are those with which Microsoft or Shavlik have flagged as being truely irrelevant? I understand that irrelevant patches can also be caused by patches being left behind after filters have been removed which, to me, sounds like they should not have been marked as irrelevant in the first place - if I'm understanding that section of what an irrelevant patch is.
Nothing… new patches will be added, more will be flagged as irrelevant most likely. Irrelevant patches should not re-appear.