Yes, listerine is an antiseptic, I keep a spray bottle with diluted Listerine by my cage and spritz the snakes after outside play time. If you are wanting to kill mites on an already infected snake, it takes about a week and several soaks in the solution. Mite as well use PAM because it's faster. It's great for cage treatments, wounds and the like. Do a little google research with a search of Listerine for snakes or something. There is a lot of good info out there.
Oh and you know Listerine was a lot of things before just a mouth wash. It was invented as a cleaning agent for doctors (I think). But none the less, look up the ingredients. It's an all natural product to this day. I fact if you get bit, it makes a great way to disinfect the bite. It is you and your snakes friend. Keep a diluted spray bottle by the cage, you'll be surprised how much you use it.

Oh but ONLY get the brown stuff!!!!!