Determine whether the set is well defined. the set of people who wear expensive perfume.

Yes, the set of people who wear expensive perfume is well-defined. A set is said to be well-defined if its definition assigns it a unique value. Otherwise, the set is said to be not well-defined or ambiguous."Well-defined” means that any given object in the entire world, whether abstract or concrete is either an element of the set or isn't.