I'm fed up of them.
There was a jokey thread a while back about AIBU by stealth but mumsnet seems to be having a rush on them at the moment.
AIBU yes you are BUT BLAH BLAH BLAH oh well in that case yanbu but you should have told us all in the first place.
I think AIBU threads should be like the classifieds.
With a 'read this before you jump in' bit. Which will list everything you need to consider before posting an AIBU.
Such as:
Full facts
More facts
Any relevant other facts
Any facts that might not seem relevant now but will appear very much so after a couple of responses
Any other facts that are totally irrelevant but might one day be relevant to another totally unrelated AIBU thread.
Grrrrrrrrrrr.