I said yes but I meant no. You have no clue why they aren't wearing deodorant, they could be allergic or they sweat so much that it doesn't help 

I think it would totally depend on the situation. I was in the military and was astounded at how many had poor hygiene habits due to just not knowing any better. Most of them knew they smelled, but didn't know what to do to fix it. If you are going to say something at least have solutions! Hypoallergenic soap (both bath and laundry) recommendations, guidelines for how often to wash clothing worn next to skin and deodorizer balls for shoes and the like. Most of the time you'll find that the really just don't know how to fix it and were never taught any better. 

If it's my lover I'll tell them they stink.  Everyone else I just keep it to myself and try to back away if it's too bad. This includes smokers, not just other  odors or bodily odors 

If its family or friends then yes but if it's a total stranger then no. I would expect my friends and family to tell me.

I tell my boyfriend and sister. And if a good friend asks me if they smell and they totally reek I say maybe get some deodorant 😂.

My husband: yes. Others, probably not unless they ask. Deoderant can wear off! If it's someone in close with and they always smell, I might ask them. But it really depends.

Someone I know yes. Random stranger no I'd just get away from them