Lord Spandex Masher,
You have piqued my curiosity. In my company, calling in unfit to fly requires a written explanation to the respective fleet chief / head of cabin operation - no less, but no more either. And such an explanation will satisfy everyone involved, if credible, so there will be no hurt feelings on any side. This is what Standby duties are for, amongst others.
So I cannot help but wondering: What presumably horrifying prospects do F/As face in Your company under the same predicament?