I was just reading a great article about items you should never put in your dishwasher - some I knew (cast iron, plastic, painted plates), others I had no idea - like kitchen knives!! the soap dulls your knife!
Check it out:
8 Things You Should Never Put in Your Dishwasher –
(click link for a full explanation)
1.Anything Wood
2.Cast Iron
3.Aluminum Cookware
4.Copper & other precious metals
5.Non Stick Cookware
6.Certain (most) plastic items
7.Kitchen Knives
8.Fine China or Painted Plates