[ufo]

Fair enough. However, it is possible that the microbiome that results from showering could be more deadly than the one that results from not showering - its not only a matter of how many bacteria there are but also what kind of bacteria they are.

[pinko]

This is the key point many people miss.

Assuming a basic level of sanitation, less faecal contamination (there is never zero) + less bacterial competition may be worse in practice than more faecal contamination + more bacterial competition.

The key advance in urban human sanitation, as I understand it, was not the use of surfectants so much as getting the open sewers off of the streets.

But I am not an expert on such things. I'd be grateful to be corrected by anyone who is.