Has anyone ever heard of this? When I worked at a service station at the age of 17 a mechanic did this on every tune up and swore by it. The customers would watch as he poured water down the carb while reving up the engine and a cloud of smoke would come out the exhaust. The engine would run smoother after doing this procedure but I've never seen it done again. Mind you they were carburated , not fuel injected cars that he tried it on.
Yeah...this is basically the same as seafoam just cheaper and alot less effective. Do be aware, that its also a damn good way to hydrolock an engine if you do it too fast, and if you do that, HAH, you be screwed.
seafoam is better, through a vaccuum line...slowly.