Final answer:
A key disadvantage of covert ethnography is the difficulty in gaining access to the social group and the potential change in behavior due to reactivity.
Step-by-step explanation:
A key disadvantage of using the covert role in ethnography is difficulty in gaining access to the social group. Researchers must pretend to be something they are not and go through a process of role-playing, making contacts, networking, or applying for a job to become an inside member of the group. This can be challenging and time-consuming.
Additionally, the problem of reactivity is a concern in covert ethnography. People may change their behavior if they know they are being observed, which can affect the authenticity of the data collected.