Usually the rule goes something like this: Clear ingredients (martini, manhattan) -- Stir Cloudy ingredients (aviation, sidecar) -- Shake Clear drinks are supposed to have an almost pristine look to them, which shaking fouls up, as well as a clean mouth-feel, no bits of ice, no froth or foam on top. Drinks that use cloudy ingredients in most cases involving fresh juices are already cloudy so it's just as well to go ahead and shake. edit: also, water isn't necessarily a bad thing in a drink, shaking and stirring are both doing two things for your drink, cooling it down and distributing water which cuts the bite of the alcohol and helps to blend flavors.