One thing worth noting with Globals is that there are a LOT of chinese knock-offs going around and there have been for several years. I had a colleague buy some from an online shop that looked kosher but the knife set was a knock-off.
Never put one through a dishwasher myself, horrible caustic things that they are. Wouldn't put my WMF cutlery in there either. In fact I'm surprised the Global didn't fly out of the dishwasher and stab you in the face for subjecting it to that
But I wouldn't expect one to rust, the alloy Yoshikin uses should have good corrosion and stain resistance properties, have you been buying knock-offs from Fleabay Ben?
Dishwashers will pit and oxidise any stainless steel eventually, some alloys may be more resistant, but equally corrosion resistance may compromise hardness, ability to hold an edge etc. I don't claim to be a metallurgist so can't comment specifics but I know there's a lot of skill in manufacturing steel with particular properties. I don't put any of my knives through the dishwasher, I clean them quickly straight after use, that includes my cheaper knives.
As an aside, best edged knife I ever tried was an old single edged carbon steel sashimi knife. A friend of a friend owns a sushi bar in Hiroshima and he was showing me how to slice sashimi, that thing was cack-your-pants sharp.
