For most people, the reason they use a deodorant is to eliminate body odor. Many deodorants will contain a scent to help mask the smell. For some people, this scent will clash with their cologne or perfume, so an unscented deodorant will be preferred.
Most, but not all, brands will provide the consumer with a choice for scents. Some advertise a “Fresh Mountain Scent” or “Rugged Masculine Scent” or “Sweat Feminine Scent” or some such advertising slogan. It just means that the deodorant has had a scent inserted during the manufacturing process. All deodorants start as an unscented product, the scent is added to help cover the body odor.
If the only scent you wear, is the scent that comes from your deodorant, then using one that leaves a faint scent may be acceptable. But if you like to wear cologne or perfume, you may inadvertently overdo the level or clash. If you work in a closed environment or crowded office, having perfume and a scented deodorant may overwhelm your coworkers.
So more and more people are switching to an unscented deodorant, because it will not clash with the cologne that you are wearing. They go by the slogan that less is more.
If you are an active hunter, you probably realize that eliminating the human smell will help you get closer to the wild game; so many hunters are also switching to an unscented deodorant to eliminate their personal scent.
When hunting members of the opposite sex, many people are now going with the theory that natural bodily scents are attractive, so they will use an unscented deodorant to eliminate the harsh, excessive smell, but still have a natural scent emitting from their body.
It comes down to personal preference. Some people prefer their deodorant not to smell, others like the scent. Either one works, so just pick your favorite.