I think you're on the right track with the telepathic aspect. Suppose it's not a scent at all, but simply a vapor? A drug delivery system for a telepathic chemical that allows the telepathic expression of the desire the host feels for the object of affection? And it's used as a spray so that the user has to consciously utilize it, as opposed to something that always must be controlled to prevent sub-conscious expression of desire and wild uninhibited surprise shagging on the subway.