If they don't already exist, there's got to be a market for dishwashers with a built-in clean/dirty indicator. With smart appliances nowadays, it doesn't even have to be a physical display (in the home.)
So many people in an office open the clean machine, remove one mug, and then close it again.
Should the machine now show dirty or clean?
[1] No readonable person could possibly consider begin to fill it before it’s completely empty, right?
The heat of the items gives a clue, as does the number of clean looking items, but there are ways to break that system.
I guess now I will.
I think the only problem would be if someone removes the last clean item and adds a heavier dirty item at the same time.
How would a machine even detect such situation?