That's a good point, if he's closing it every time it might be some kind of odd blindspot in processing, but still not stupid or incurious.

I wash by hand. Please convince me to use a dishwasher?

Meanwhile, I know people that should just not use a dishwasher bcz they can't load it properly. Honestly, dishwashers are bloody useless. Washing by hand is faster and cheaper.

If it gets stuff clean, you aren't really using it wrong.