To resign or not?
Every player, even Carlsen, gets into hopeless positions. Should one resign in a clearly lost game? It is true that no-one ever won by resigning. Also, if maintaining your rating is your fetish then you should play on till you are mated, as there is always a chance that the opponent will time-out.
The other side of the story is that playing on in a hopeless position is highly unpleasant. It saps our emotional and mental energy and is demoralising. If the other guy outplayed me from the start, has a better position, is up a piece, and I have no apparent way to improve my position, then what is the point of playing on? Why endure a long drawn-out but nearly inevitable defeat?
It comes down to personal preference. I hate to play on just in case my opponent makes a huge blunder. I prefer to call it quits and start a new game, hopefully having learned a lesson.