I've seen this one come up a lot in advice columns, and the consensus seems to be that you should only bring it up if it's significantly impacting the person with the odor. Is it impacting their job performance? Are customers complaining? Is smelling good part of their job description? Does your company actually have a hygiene policy?
If not, then the solution starts with you. How can you avoid it? Can you learn to just live with the smell? Is it really so disruptive that it's impacting your job performance, or are you just being sensitive/picky? I had a coworker who was from another country and constantly had an overpowering smell of certain spices, but I learned to just cope with it. I turned my desk a bit so that it wasn't right in my face all the time, I opened my window when possible, and I held my breath briefly whenever he got up or walked by. It was still annoying, but I adjusted.
If it really is a problem and not just an annoyance, then it's your manager's responsibility to talk to the person in question. They need to be careful to consider that the smell might be due to a medical problem. Most people who have odor problems aren't oblivious to them; they just don't quite know what to do. A skilled HR rep or manager will be able to help them out. But it should never, ever be a peer worker counseling them on it unless you're very close friends outside of work.