It actually worked. I used only and only water to wash. In the beginning hot, then slowly working to a quite cold shower. That helped out too.
The effect? My hair is since then never better. I have no more dandruff, no rash or other headskin condition.
The body took it very well. Using only water and a turkish rubbing cloth. I didn't smell. I even asked a few colleagues ( female too ) to tell me if they noticed something about me, and there was nothing out of the ordinary. My armpits were sweating but no unpleasant smell would be produced. Some women found me even more attractive ;), but this might be subjective.
Reason for the lack of smell is most probably the natural bacteria that eat all of my body output ( sweat, dead skin, etc ). The cold shower was keeping this bacteria alive, since hot water has some effect ( dilutuing fat and killing some of them ).
In the end, was a positive experiment. I stopp it after this 3 months, due to home arrival of my significant other :).