Have you noticed that labels saying "this cookware is not dishwasher-safe" aren't oven-proof? I have.
I managed to burn a label off, by leaving it on a dish when cooking in it. Of course, I then didn't realise that the dish wasn't dishwasher-safe, and it had to be thrown away after I put it through a washing cycle.
There must be a trick to this, but I haven't discovered a single rule that I can use to say "this type of dish is never safe for dishwashers".