why would you save anything considering you're AT BEST getting back what you have prepaid for? if anything, it's, more often than not, a cost to you - the water wasted on washing the cans and bottles (if you bother), the real estate space wasted on temporarily housing the washed bottles and cans before they're returned and the time wasted on queuing at the return right machine, especially if you're behind someone with 200 to return.
my household does not do packaged beverages, so it makes no difference to us. but i have to hold my breath whenever i pass by a return right machine, which oftentimes gives off a stench.