I have never tried it, and wouldn't for many reasons. First off, I don't even wash dishes in my dishwasher! I know it gets hot enough, but how does it save money? Even if you use foil to cover the baking pan in the oven, you'd have to use a whole lot more of it to bake in a dishwasher.
You wouldn't be able to fill the dishwasher with as many dirty dishes, dishwashers aren't exactly cheap to run, the hot water heater first has to heat the water, the dishwasher runs for longer than it would take in the oven, if you accidently didn't get it sealed extremely well you could end up throwing it all out.
If they really wanted to save money, not just get on a tv show, I'd think they would just bake double lasagna and freeze one, or bake bread or something else was long as the oven was on.
But then, I've never fried eggs in my toaster either. Guess I'll never get my 15 min of fame for being a nut case.