On Diswasher Affordances

Dishwashers can be
a tricky beast: how to tell
when clean or dirty?

At home it's easy -
red means "dirty, don't use me!"
Doesn't that make sense?

But at work, red means
"Dishes are clean! don't put in
any more dirties!"

Confused and baffled!
A cutlery explosion!
Poor Lisa panics!!