Factual products like newspapers should avoid bias as their goal is to present strictly factual, non-fictional information. However, some bias may be acceptable in advocacy pieces like charity campaigns if used to effectively promote a valid cause.
A 2011 Daily Mirror article about comedian Frankie Boyle contained a biased claim that damaged his reputation. This shows bias can defame individuals in factual media. However, campaign posters like PETA's fur poster use emotional language and images to advocate for animal rights, so some bias promotes humanitarian goals.
While journalists should avoid personal views, bias may be acceptable in advocacy pieces if they also provide factual information to make their argument believable and informative rather than just propaganda. The line between acceptable and unacceptable