Moreover, you don't know the incongruency principle of how detergents work: they only clean when there is dirt. If the dishes are nearly clean, the soap enzymes yield less and all you will have achieved with your hand pre-wash is increase water and energy spending. The OCU (Spanish Consumers' and Users' Organisation) proved this, and advises people to skip the water and use a paper towel or a wet sponge to remove leftovers. Remember to put the dishwasher on when it is fully loaded and with the right amount of detergent to ensure energy saving. More detergent does not mean that it is better.