Dishwashers are boss at cleaning dishes without getting your hands wet. They're also a perfect home - because of their hot and moist temperature - for black yeast to grow. Black yeast, as you can probably imagine, is not very good.
Black yeast is rarely found in nature but apparently thrives on the rubber lining of dishwashers. Though dishwashers can get uber-hot and use a lot of detergent (which should theoretically kill off such things), the black yeast in question, Exophiala dermatitidis and E. phaeomuriformis, are "remarkably tolerant to heat, high salt concentrations, aggressive detergents and to both acid and alkaline water", which is to say dishwashers are their home sweet home. In fact, studies have found that 62 per cent of dishwashers contain fungi on the rubber in the door (and 56 per cent of that fungi being the black yeast).
It also doesn't help that Exophiala dermatitidis is flat out scary, they're known to play a role in pulmonary colonization of patients with cystic fibrosis and can cause fatal infections in human. Having invaded our dishwashers, they must've underwent an impressive evolutionary process to adapt to our dishwashers. Maybe it's time to wash our dishes ourselves. [PhysOrg]