I'm pretty good at noticing my own BO, I'm real sensitive to it. That's not to say I don't eventually stink like usual by the end of the day. But after a shower? I certainly don't have BO because I wash that all off.
Your point is that is that if you don't use soap, you'll have BO! When in reality, soap smell wears off - real quick, real fast. Most of the smell you put on occurs after a shower: deodorant, cologne. Your claim is that you know people who claim they didn't smell after using deodorant? Of course they're full of shit. Deodorant masks musk. But soap? You think people will smell because they aren't using soap in the shower? On what basis? How? How is there a difference between using hot water and a washcloth/sponge and a washcloth/sponge with soap? If you're scrubbing, and using water, you're still getting dirt and excess off of your body.
So your point about people smelling is a total random one and irrelevant one, especially when someone who is not using soap DOES use deodorant.