It's the whole "alter a person's will thing" that seems the assumption here. As there are no real human pheromones, and as it isn't explicitly stated how the spray works, why would it necessarily follow that the spray would somehow change a person's will? Or, for that matter, introduce chemicals into another persons body without their consent? It's just as easy to assume based on what we see in the episode that the spray works on Owen alone, after all, he sprays himself. The result of the spray, IMHO, simply makes him more attractive.