I just learned this and thought I'd share since it involves my 2 most favoritest things in the world, Baking soda and Vinegar!
I have a hard time with my dishwasher leaving dusty residue on my dishes, its really lame and makes me feel like I wasted resources by cleaning them since I just have to rinse them again.
Well try this on a load and see if it works for you:
fill the dishwasher (NOT TOO FULL, or the washer wont be able to do its job anyways) then sprinkle a little bit of baking soda on the inside of the door. Fill the rinser with vinegar, and put about half as much detergent in there than you normally do.
And thats it! Let me know how this worked out for you! It worked for AWESOMELY, and I thought nothing could make that problem stop!