Luckily, they're pretty easy to clean.

A man loads the top rack of a dishwasher. Top racks are best suited for items that are more sensitive to heat. (Carlos Avila Gonzalez/San Francisco Chronicle via Getty Images) The science is in.

A dishwasher can silently accumulate years of grime without giving off any unpleasant odors to alert you, even if it hasn't been cleaned since being bought five years ago. Without a stink, a grimy ...