I lost this thread and thought it had been removed, fab found it again.
Worried my story won't live up to expectations! 
This will probably out me, as it's a fairly well known story.
Used to work in a posh salon where there was a v v tiny loo, for staff. No window, built into a corner.
Someone ( female and not staff) regularly did awful, pooing in the loo, on the loo seat everywhere, never flushed!! Left it there for all to see. It was so horrible. It took us ages to work out the offender. Even saying the loo was out of order didn't deter this person. She would sneak past us to use the loo.
One time we found the mess, we were in the middle of cleaning it up whilst gagging, and she pushed us out of the way to create more mess.
I understand the "if you've got to go ibs thing", but why not flush or attempt to clean up your mess. We all felt this was a behaviour thing, as she was only in the salon for 5mins.
But the worse time was when we found she had used the bin in the tanning cubical for her liquid shit!
My point was that it's not only men who have weird poo behaviour.