This essay starts by accepting Cécile Fabre's argument in her book Spying through a Glass Darkly that intelligence work, including using incentives and pressures to encourage betrayal and treason, can be morally justified based on the criteria of necessity, effectiveness, and proportionality. However, while assessments of spying tend to be based on Cold War notions, I explore it here in the messier reality of counterinsurgency, counterterrorism, and “new wars.” In addition, I suggest a methodological expansion: adding a sociological perspective to the ethical discussion by exploring the wider effects on society, over longer periods, of the operation of informers. Based on these shifts in perspective and context, I identify additional social harms generated by espionage that should lead to a more restrictive view of ethical espionage than the one emerging from Fabre's work. I argue that many of these social harms are created by the mass recruitment of informers, in asymmetrical conflicts where governments have leverage over suspected communities, and given the (often mistaken) belief that everyone recruited to act as informer is an “asset,” primarily providing advantages. I argue, therefore, that the decisive issue is one of scale: many of the ethical problems created by espionage in these contexts result from the widespread systematic recruitment of informers, while small-scale, targeted, ad-hoc recruitment can more easily avoid such problems.