For a while, my roommate and BFFL touted the benefits of baking soda as a deodorant and as a toothpaste. Even before I made the switch, this isn't that far fetched since it is in every toothpaste brand you can find out there, and in some antiperspirants as well.
Apparently, some people think sodium fluoride is some bad shit. According to these sources, it has been used for a lot of bad shit, and Nazis poisoned the water with it. Then there is Operation Paperclip (google it) and a host of other shit you can find about how bad fluoride is.
If you are anything like me, you might wear black shirts a lot. You might also get this weird white caking from your antiperspirant. Even if you use the shit that "goes on clear and won't fuck your shirts up." If you have half a brain, you know most advertisements aren't true. Well, those advertisements aren't. I sweat like a whore in church, and I have fucked up a lot of shirts.
Since the change, I have not had any fucked up stains on my shirts, and no matter how much I sweat, I do not get rank like I used to, even when I go to the gym and hit PRs like a motherfucker. On a day where I am inactive, I can skip bathing and still not get rank, which is something I was never able to do in the past. Needless to say, baking soda is pretty fucking cool.
And to top it off, a gigantic box of the shit costs less than a leading name brand of toothpaste or deodorant, and will last at least ten times as long. And you don't have to go to a hippie health food store and by some overpriced "natural" bullshit that they are marketing, or listen to them yack about all the aluminum and other bullshit in the deodorants on the market (since you can find that info for free anywhere).
You can test about anything, I chose this subject because it has saved me a ton of money, and has made my life better in a big way. Plus, baking soda is useful for a bunch of other shit too, like baking, or keeping your fridge smelling good, why not have a bunch of it around? It's probably as useful as water.