Shaming people's natural body odor shouldn't be the norm.
It's quite distasteful and intolerant in fact (even sometimes a clear sign of racism). If someone gets offended by someone's BO, I would suggest them to reevaluate themselves as a human being and try to be tolerant of other's human nature.
I shower irregularly, when needed. Obviously more after a special sweat inducing effort or getting dirty outdoor. I don't stink, I smell human.
I find it offensive that someone would be so insensitive to have the nerve to express a displeasure at my natural body odor, when most often than not they would be the ones flouting a strong headache inducing chemical deodorant and/or perfume smell.
Living in a diverse society doesn't mean that everybody should be as bland as possible, but instead that efforts have to be made to be tolerant of others as they are.
So F* your teacher, shame on them