"The proof of the pudding is in the eating/tasting." True. That determines if the pudding is edible tasty delicious. But if it isn't you have other things to consider.
The cost of the ingredients
The time and effort of the person who made it
The good intention of pleasing someone
Though they may all have been for naught and the pudding had to be thrown out do we discount it because it was a failure? That seems harsh and unkind. I think effort and intention is worthy of mention and counts for something. Said by a person who has thrown out a few things that were a disaster.