Since humans are animals the natural sexual scent attraction known as pheromones especially in women is extremely powerful. On the same premise humans don’t always have sex to breed, in fact most people have sex for pleasure, love and fun.
The scent of sexual smell knows as pheromones can be masked by cologne as well as men using baby powder and deodorant; they all mask the true sexual scent of a man.
The majority of women who marry and have children often don't pick their mates from smell. A true biological match in a male and female where the female is drawn to the man because of his sexual smell alone. Although the reality of finding that perfect biological match is not always an option hence a great cologne and the fact that our brains override our animal instinct usually takes over.
A man could be a true biological match for a woman but not have the mental, social or stability factor. At that point the female brain takes over or at least it does in most women chosing their partner. For some women it may play itself out as lust in the beginning or "love at first smell", only to realize later indeed that the sexual attraction was just lust. The attraction was purely based on pheromones.
The human system is remarkable, If a woman meets a man she likes but hates his natural body smell, this could be an indication of a bad genetic match, so wear protection and get your blood tested before having children.
One last bit of advice, a man's natural body scent after a shower can be erotic to a woman, but after a full day's work and no shower even if you are a biological match your smell is no longer attractive.
Women Can Smell Genetic Differences
Experts believe there are two major reasons for preferring a mate with different genes than your own. The first is that parents with more diverse MHC genes will give rise to offspring with better immune systems, and the second is that by avoiding mates who have very similar MHC types, you also avoid inbreeding.