Bad manners in populism: Populists might rely on provocation and aggressive rhetoric that sets them apart from other candidates. Their bad manners emphasise agitation, spectacular acts, exaggeration, calculated provocations, and the intended violation of political and socio-cultural norms. By bad manners, scholars refer to the coarsening of political rhetoric and a disregard for both appropriate modes of acting in the political realm, directness, playfulness, bullying, obscenity, disrespectful languages—and are ready to resort to anecdotes as evidence and to show a studied ignorance of that which does not interest them.

Sources:
Moffitt, B. (2016). The Performative Turn in the Comparative Study of Populism. American Political Science Association Comparative Politics Newsletter, vol. 26, issue 2, pp. 52-57.

Nai, J. M. (2019). Can anyone be objective about Donald Trump? Assessing the personality of political figures. Journal of Elections, Public Opinion and Parties online first, pages 1-26.