Swamp coolers work great and use a fraction of the electricity of an air conditioner in a dry climate with little humidity (like Phoenix) but there are downsides like mold and, well, everything feels wet in your house. Dry cool air is more comfortable than wet cool air.
Why don't the condenser units of a split system AC use water in some way to cool the condenser? Is it because the moist air would cause corrosion faster and the savings in electricity would be lost to the fact that you'd have to replace the unit? How do AC units in climates like Florida last more than a few years since it's humid all the time there?