Lightly salted water tastes like tears. Thoroughly salted water tastes like seawater. For foods that absorb a lot of water as they cook, like beans or pasta, lightly salted is the way to go, since your aim is to draw out the natural flavors of the food, not to make them “salty.” For foods that don't absorb water, such as green vegetables, the point is to use salt's properties of sealing in nutrients, color, and flavor. For that reason, you would salt the water more assertively. Excess salt can easily be washed from those vegetables. Make no mistake, though: Salt is an important part of coaxing the best flavors from your good ingredients.