Old People Smell: is that the body turning more acidic from long term inflammation

And subsequent decay?

A lot of old people have a default smell that soap and perfumes cannot eliminate nor fully cover.

Teeth and gums also oftentimes have a smell even if overall healthy.

Hair thins from inflammation and poor cell turn over and the hair does not smell shampoo fresh for long-term washing it.

Sweating from exercise has a different smell then when a 30 year old exercises.

Can someone break down what causes this and how we can stop it from happening?