From Reign of heretics – Arianism and political power in the Vandal and Ostrogothic kingdoms by Christopher J. (Christopher James) Nofziger:

Although a few schools of thought followed lines similar to the teachings of Arius, the label “Arian” acquired negative connotations after Nicaea. The practice of attaching recognizably “deviant” titles to groups considered theologically or socially unacceptable makes it difficult to identify the actual beliefs held by these groups. Often, clergy would incorporate many distinct factions together under a single name, creating a convenient opposition against which the Church could define itself. The widespread use of “Manichaean” or “Pelagian” enjoyed similar usage, acting as a convenient “known” heretical label to which people could attach negative connotations. Even the Eunomian Philostorgius classified members of the Homoousion (Nicene) movement as “Arians.” The diverse applications of such terms, when held alongside their negatively charged associations and rhetorical use, cannot be necessarily held as indicators of an internal identity within these groups.