If you're not doing this [running hot water] before you start your dishwasher, I hate to break it to you, but you're not doing it right.

By running hot water at the sink before you start the dishwasher, what you're doing is priming the lines with hot water. That way, when you turn on your dishwasher, it instantly fills with hot water and it's going to optimize your cleaning results. So before you put in a service call for cleaning issues with the dishwasher, go ahead and try this first.