You don't really have to have a good nose to pick up the scent of cheap cologne or deodorant. It's kind of... there.
I think it requires a degree of intelligence and maturity to pick out a nice scent and use it wisely and that's part of the problem.
In a way, scents are a very intimate, personal thing; people pick a scent that appeals to them. As a result, you can tell a lot about a person from it. For example, there are various perfumes and body sprays that have a very sultry vanilla-musk-candy scent. They almost all have some sexually-related title ("Burlesque", for example). I don't know anyone who wears them very often, except for a couple of girls. To me, it smells like $5 streetwalker perfume. When I smell it I automatically think someone is trying to subtly (or not subtly) walk on their sensual side. I happen to know both of those girls struggle with the temptation to flaunt their sexuality. No offense to anyone here who wears it, but that's my experience.