… one can ‘finish’ a mix over their half decent monitors, bounce it down, listen to it the next day on absolutely rubbish wee desktop speakers and come up with a list as long as their arm of things that they need to go back and fix?
In the words of that meme from a few years back…
true that!
Indeed, in fact it seems to happen to me even if I come back and listen on the same monitors later. 
Too right. I have learned the hard way never to post a mix on the day I tell myself “yeah this is done enough to post.” I sleep on it for at least a day first and listen on every system I have, and invariably, come up with that list of needed fixes. Happened just this morning while I was listening to my rev of Paralysis by Analysis from last night in the car on the way to work, in fact!
It always blows my mind how easy it is to find faults in other peoples mixes, but then turn around and do the exact same thing.
Yes, that’s a universal issue - I transferred this article I first wrote for Recording Review over here - it deals with the very subject:
http://wp.indierecordingdepot.com/5-stupidly-expensive-ways-to-turn-cloth-ears-gold/
So glad you ported that over! Gonna read it again tonight. Very nice piece Andrew. 