Je recherche toujours ceci quand je fais des copier-coller depuis Word vers Vim.

En anglais.

Alternatively, you can place your cursor on the unprintable character and hit ga, it will show the decimal/hex/octal code of that character, then you can substitute it with:

:%s/\%xYY/substitute/g

where YY is the hex code of the char, if it's multibyte:

:%s/\%uYYYY/substitute/g