We did a study to determine if there really is an old-person smell. And in fact, evaluators could tell, based on scent, whether samples were taken from someone over age 75 or someone younger. But contrary to some older people’s fears, those evaluators did not consider the smell of older people unpleasant. In fact, they rated old people’s upper-body odor significantly less objectionable than that of younger people.

It turns out that the difference is mostly one of quantity. Adults of all ages produce fairly similar body odors, but younger adults seem to produce them in greater quantities, leading to a less pleasant result.

Of course, older people in a nursing home who are no longer ambulatory might have trouble washing themselves, with predictably malodorous results. You might ask the staff to wash your father more regularly. Also, our salivary glands tend to produce less saliva as we age, which can encourage the growth of foul-odor-producing anaerobic bacteria in our mouths. Suggest to your father that he gently brush his tongue every day in addition to his teeth.