Put a drop of chocolate sauce on the inside of the door, if it's still there the dishes aren't clean.
This is exactly why I didn't buy one of these or the Amazon version. I didn't trust that the devices would work as long as they could function and was correct.
The heat will just dissipate in the air, and they can launch it at night when it's colder. Science!/s in case, there are a few mouth breathers out today