Actually there was a 60 minutes type article on this a few years back. I'd remove the screens and look underneath. You should clean these at least every 3 months or so..
Dishwashers are for suckers and professional consumers (which is what most 'mericans have become). It's actually easier and healthier to clean as you go. Don't shoot the messenger. Just trying to point out the ridiculousness of these contraptions and maybe save a life or
2.....Geez...