No not demand to pay at all - I totally agree that the person had full intentions of paying for the coffee as they went to the cashier but when the cashier said have a nice day and the poster knew that they should have paid, at that point, I personally would have said something along the lines of 'I am not using a current mug, this is last years, how much is the coffee?' I know not everyone would do this but I would rather this than for the cashier to take a double check and call me out to pay for the coffee if they realised, that would have been embarrassing!
Yes it was the right thing to do to go to the cashier but when waved on, knowing that they should have paid and didnt say anything but continue to walk away without paying, thats just not right to me! Im sure that the CM turnaround is vast and maybe they didnt realise it was an old mug, but for me, knowing it was an old mug, I would point this out to them whether that is their job or not, maybe I am just too honest!
On that note, I apologise to the poster of that comment if you think my reply was harsh, I am an extremely honest person and I would have been embarrassed walking away knowing that I hadnt paid but if praise is in order for at least offering to pay then well done for offering but I wouldnt change what I would do and in this instance, that would be to point out my old mug!