Re: how to tell a loved one that they have bad body odor
I would say it depends on the person. Are they sensitive and easily hurt? Would they have a sense of humor about it, if you jokingly said, "I love you, my dear, but I have to let you know your deodorant is failing. What brand do you use?"
The important thing is to not mention it in front of other people, and approach it in a way that will be least likely to hurt their feelings, based on their personality. If they use a deodorant only, you could say, "I like brand such-and-such antiperspirant." Or tell them that you read in an article that they work better when applied twice: once after the morning shower and once at night.
There might be another reason, like they want to avoid the aluminum found in antiperspirants (some people believe it is a health risk), or they may be depressed and not taking care of themselves, etc. If the person is depressed, they need to be helped medically. If they are just not using a good brand or using it often enough, and you live in a hot climate, they might just need some suggestions. It all depends on the details...
So in other words, don't say, "by the way, you smell bad all the time. Don't you use deodorant?" Approach it as, TODAY you just happened to notice their deodorant failed. What brand do they use? It could become a non-hurtful conversation. Good luck!