For many within the coffee world washed coffees are considered the gold standard.
Coffee cherries are first pulped in a machine called a pulper (creative, I know) which removes the outer layers of the fruit leaving behind the bean and mucilage. The coffee is then fermented in water for a time (usually one or two days at least) and then washed to remove the mucilage.
The washed process is regarded by many as producing a superior coffee compared with other processing methods, however the process requires a great deal of skill and water to produce, making it costly and also far less environmentally friendly than the Natural method.
As the fruit of the cherry is removed so early in this process the flavour profile is quite unaffected by the fruit meaning varietal, soil, weather, ripeness, processing skill, and drying are of the utmost importance in determining cup quality.
It is for these reasons washed coffee is considered so highly amongst coffee professionals - a good washed coffee displays a level of care and skill, an attention to detail, and a love of coffee that can't be ignored.