Food for Thought
Should I tell someone they have bad breath?
You notice an unpleasant smell on someone's breath during a conversation. If you say something, the other person may feel embarrassed. If you say nothing, you may deny them the chance to do something about it. What would be respectful?
The question is less trivial than it sounds. It is about honesty, consideration and the boundary between a helpful observation and an unsolicited judgement.
An observation is not yet an explanation
I can notice a smell. Initially, that is all I know. I do not know what caused it or whether the person has noticed it themselves. Bad breath can have different causes. The UK's National Health Service (NHS) lists, among other things, food, problems with teeth or gums, dry mouth and certain medical conditions. A perception cannot establish a diagnosis, let alone a judgement about someone's character.
The first question is therefore: What have I actually noticed myself, and what am I merely assuming?
When mentioning it may make sense
Before saying anything, I would consider whether there is a relationship of trust and a private moment. Am I prepared for the person to react negatively? And can I stop if they do not want to discuss the subject?
One possible opening would be: “May I mention something personal? I noticed an unusual smell on your breath during our conversation. I wanted to tell you discreetly.”
This sentence is a suggested way to start a conversation, not a scientifically tested method. It can also be left unsaid. Not every observation needs to be voiced. For me, commenting in front of others, making a joke about it or offering an unsolicited theory about someone's hygiene would not be respectful alternatives.
In an employment relationship, there may also be an imbalance of power. A manager cannot say the same words under the same conditions as a peer. Discretion is therefore especially important.
What I know and what I stand for
Established finding: Bad breath can have different causes. The other person normally cannot know which one applies.
Assumption: A considerate remark might be welcome. Whether it actually would be remains uncertain.
My position: A person's dignity must not depend on how pleasant an encounter is. Honesty should help, not merely relieve one's own discomfort.
The bigger question is therefore: When is silence considerate, and when is it simply avoiding conflict?
To think further: How would you want someone to draw your attention to something uncomfortable, if at all?
Further reading: Hosang Consulting's principles and Collaboration and leadership.
Sources and limitations: NHS: Bad breath, on medical causes and when to seek advice. The suggested conversation is a matter of personal judgement, not medical or employment-law advice.