Just installed a new diswasher for a neighbor. It has a loop on the discharge tube, on the side of the dishwasher, which prevents backflow from the disposer into the dishwasher...which would be really bad. However it does not prevent crud from the disposer, or sink, getting into the discharge tube and making it smell. Therefore, a high loop in the cabinet is still required, unless you have an air gap (that thing on top of the sink that gurgles when your dishwasher is running.)
