A hack writer is a writer for hire, paid to express others' thoughts or opinions in felicitous verbiage, often in the form of political pamphlets. Some such writers are very talented. Nonetheless, in one vernacular usage, a hack is a person lacking talent or ability.
Example Usage of writer
discopunkk: #WorldsThinnestBooks "Why I Really Am A Great writer" by Russell T. Davies #torchwood
ShadowCastAudio: Got some awesome news today. Major established writer (11 books published) committed to the podcast. Recieved his submission today. Woo hoo
FiscalFizzle: RT @MattJabs: Watch @ConsumerismComm this week for guest posts from finalists @flexo has for CC staff writer position. It'll be a showdown!