Maybe I shouldn’t take advice on what’s hygienic from someone with your username, lol, but you’re probably right. IIRC, didn’t Mythbusters do an episode on dishwasher lasagna… Don’t most commercial dishwashers get hot enough… I wouldn’t do this because I don’t use my dishwasher much and in the long run I doubt it saves much money anyway, but I think this was one of the less weird things on the show, minus the ingredients. This is an old story the producers probably “re-enacted“.