An invisible thing can't be seen, but what do you call something which cannot be smelled?
unscented, means it hasn't had any scent added.
clean, means they're recently washed.
inert, means it's unreactive and won't stimulate those nerve-endings.
3 : deficient in active properties; especially : lacking a usual or anticipated chemical or biological action
odourless, (odorless) free of odour