I know that. But, without context, if you hear about someone that his "personal hygiene left much to be desired", it just means "he stinks", right? Then when

I know that. But, without context, if you hear about someone that his "personal hygiene left much to be desired", it just means "he stinks", right? Then when you write about Middle-Age peasants who died for some lack of understanding of contagion mechanism, you do not write "personal hygiene left much to be desired", unless you want to be ironic, sarcastic, or whatever figure de style you are trying to add.