I have concluded and deducted that the 'rule" reads as follows: The better the quality of light/ cloudcover or cloud structure there is in a sunset or sunrise, the greater the odds are that you will be at work. This of course applies to those of us who have a normal day job. I formulated this rule on Saturday morning ( after countless similar experiences) just before six am, when I happened to walk out the office and gasped at the colours in the sky that weren't there twenty minutes before. Photo taken with the crap cellphone I carry.
All tongue in cheek of course but hell, I've had enough days like these, after waiting for a week for some colour in the sky- only to have a show put on when I have to be at work, the very next day.