Observation and acute listening. When a woman dolls up, its for the ladies.
Have you ever seen a man that gives a rat's behind whether two women are in the same dress, or whether another man is wearing the same shirt he is?
Have you ever heard a man say, "I can't believe she is wearing that?" (lycra on 300 pound women excepted)
Why can women tell you what every other woman was wearing at a party that occurred two months ago?
Well, for one thing, we have a far keener eye for detail and a better memory for detail. And those two factors make detail more interesting to us than to men, I suspect.
Have you ever asked yourself why a woman would ask a man something like "Do I look fat in this?" Think about it. My post #203 to Edward is a good starting point.