the way i see it all stereotypes which are imposed on a people are negative, the only potentially good stereotypes are ones the a people themselves chose to identify with.
Even then, "positive stereotypes" embraced by a community still cause a lot of harm, especially when those stereotypes originate outside the community. Like Asians being "model minorities" or Black men having "BBCs"
The former is a form of divide-and-rule mentality (like the British empire marking certain 'races' as 'martial races' and effectively creating a racial heirarchy), the latter is objectification, fetishization and yes fearmongering to leverage human nature as a way to make racism part of culture.
I don't know about fear mongering, because that's quite specific, but those ideas were deployed by racists in order to further their own racist agendas.