So I decided to buy some of this stuff:
I figure I could always use whiter teeth, and being a Listerine junky like I am I thought I would try something new. You're actually supposed to use this stuff before you brush, and for 60 seconds(!) as opposed to the usual 30. Also, there's all kinds of stickers all over the bottle that say "NOT FOR USE IN HOUSEHOLD WITH YOUNG CHILDREN" and many warnings not to swallow it. I guess it's pretty powerful stuff. After you use it, you brush your teeth like usual, during which time I guess some magical science stuff happens, making your teeth white.
Swishing it around my mouth for a full minute is proving to be difficult though. On the back of the bottle it says "Dynamic Foaming Action tells you it's working!" because I guess there's some enzymes or metabolisms or something in there. I think instead it should read "Dynamic Foaming Action tells you that you have a nasty swig of lukewarm and increasingly foamy sludge in your mouth!" because that's all I know for sure. The "it's working" part is yet to be determined. It really isn't very tasty and after swishing it around for about 20 seconds, it starts to take on the texture of warm frothy spit swishing around in your mouth. This is about the time you would be getting ready to empty your mouth of normal Listerine, but this special whitening stuff still has 40 seconds to go! Forty seconds of squishing between your teeth what is quickly starting to feel like the contents of a well used spittoon. I haven't been able to complete the sixty second regiment without gagging and retching the stuff into the sink early. In fact, I don't think I've even hit forty seconds yet. It's straight up nasty. I'm going to keep using it to see if my teeth get any whiter, but if not, I will have frequently and severely grossed myself out for a couple weeks for no reason. Listerine: 1, Me: 0.