I have a very sensitive nose too, described as that of a dog by my sister, and it's not that people not using shampoo smell worse, it's that they smell of sebum and pheromones and all that stuff, which I don't mind. I smell more like an animal, and I love animals.

A few years ago I had to stay inside a lot, so I tried showering without soap on my body too, and it does seem to work better for longer than using soap, but it's less convenient and sort of less reliable I find, so I use soap again on the three key areas. My hair though, I just use water to wash. My girlfriend tried to argue with me once that I needed shampoo and she just looked it up briefly and said "I was wrong!"