Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Not Dishwasher Safe

I was looking for a dishwasher-safe cutting board and hoped that Oxo Good Grips Cutting Board was the ticket. Unfortunately, the black rubber from the edges melts in the dishwasher and stains not only the dishwasher, but other plastic dishes. This didn't happen right away, but I noticed that the inside of the dishwasher, the oxo cutting board, and other plastic dishes had black spots on them. I couldn't even get rid of the black spots. When you try to wipe the black spot, it ends up smearing and creates a larger spot.Naturally, I returned the oxo cutting boards, but all my other plastic dishes must be thrown out.