[Qwertious]

Not exactly - after the perfume is sold, the person wearing the perfume gives out the smell for free, and nobody tries to charge people for smelling the worn smell.

Obviously the bottle of concentrated smell costs money, though.

[bweitzman]

yes and no. When a person buys perfume, they don't care about the actual chemical makeup of whatever liquid is in the bottle, they care about the scent (and possibly brand associations). I would call that paying for the smell. The smell happens to come with an implied license for distributing it in small quantities in public :)