Citizen Science (or “Public Participation in Scientific Research”), has attracted attention as a new way of engaging the public with science through recruiting them to participate in scientific research. It is often seen as a win-win solution to promoting public engagement to scientists as well as empowering the public and in the process enhancing science literacy. This paper presents a qualitative study of interviews with scientists and communicators who participated in the “OPAL” project, identifying three potential flashpoints where conflicts can (though not necessarily do) arise for those working on citizen science professionally. We find that although participation in the CS project was generally valued, it does not seem to overcome continuing (and widely reported) concerns about public engagement. We suggest that enthusiasm for win-win situations should be replaced with more realistic expectations about what scientists can expect to get out of CS-style public engagement.