Yes.
I would actually feel it was my moral duty, to let them know that their personal hygiene needed some attention. If I smelled bad, and people around me didn't let me know, that would bother me. Terrible body odor is offensive, and I don't want to offend those around me by being a stinker. Especially my Dad, or Boss, the two people whom I spend the majority of my time with. Both of which, I feel 100% certainty will let me know if I smell bad. If we cannot be honest with each other, then best to part ways.