As a big perfume fan, I think about what my favourite book characters might wear scent-wise quite a lot. In fact, it's sort of my Roman empire. And lately, I've shifted my attention to the main character girlies that are being made/have been made into TV series or movies I also love. I enjoy seeing a character come to life, and it helps me to imagine each one's beauty routine and, thus, how I imagine they'd smell.
My experience with synesthesia also comes into play here—when I read and see words or watch and listen to the characters on TV, my senses become interlaced, and my nose begins to somehow pick up scent. Seeing costumes or reading about a character's personality traits help me to imagine what kind of popular perfumes they'd wear, and thus which they'd opt for if they were shopping amongst us today.
