Do you think it is right (or ethical) for sociologists to not identify or otherwise misrepresent themselves when doing research? What if identifying themselves as researchers will destroy their access to a research setting or to informants?

Ethics are the standards that essentially help us differentiate between right and wrong modes of conduct in social settings. Sociologists work with human subjects in order to gain data and insight about human actions, interactions, social constructs, and the function of human society.
Because sociologists study and work with human subjects, it is essential for them to act in an ethical way at all times. Therefore, they must always represent themselves accurately and identify themselves to their subjects when performing research in order to obtain informed consent. Informed consent means that the human subjects are aware that they are working with a sociologist, are aware of the research process in which they are participating, are aware of the purpose of the research being performed, and knowingly agree to be part of that process. Without obtaining informed consent from a subject and continuing the research process anyway, a sociologist would be committing an egregious breech of ethical codes.
For example, if a sociologist were to keep their identity secret and did not disclose their research purposes to a human subject, that person could potentially act incredibly differently than if they were aware that they were part of a sociological research project. This would be especially true in situations where information about drugs, alcohol, or sexual practices were being shared. If a sociologist didn’t disclose their identity or research project, a subject might share information more freely, especially about topics perceived to be taboo by society. This would not only skew the data collected, but it would mean that the human subject was being disrespected from an ethical standpoint, as the data collected would have been obtained through deceit. Additionally, some people may not want to have their personal information and experiences act as part of a body of research, especially if that research were to be published. In that type of situation, it is important to allow human subjects to choose to participate in research or not, as tricking them into it would be a breech of ethical codes.
This question boils down to the idea of consent. Human subjects must be fully aware of the identity of a sociologist and their research process in order to be aware of the full situation and give their informed consent. Informed consent is important because it ensures that human subjects are treated with respect and that those who interact with human subjects are held to high ethical standards.