I have to agree...this is VERY rare. It does happen, but not often at all. And usually you WILL be notified. The only time things didn't go well in my experience was when I was working the CZ over the summer and they didn't give us our Denver sleeper, and the decision had just been made that day. There was even an attendant who showed up to work for it...off the extra board...he had been called for it the day before.
Part of the reason this occurred though, was because of the equipment shortage that the derailment of the Capitol Limited caused. But now that it looks like some money is coming in, and we have Gunn at the helm, I wouldn't expect more problems like this for a long time.