What's a word that means "using emotionally charged language when neutral language could be used"?

Sounds like it might be dysphemism:

NOUN

A derogatory or unpleasant term used instead of a pleasant or neutral one, such as “loony bin” for “mental hospital.”

The opposite of euphemism

(OxfordDictionaries)

This matches up pretty well with your description of "using emotionally charged or unfairly pejorative language".

Also, you mention in a comment that "This was an obscure word - one of those dictionary.com words of the day"; I'm not sure about "word of the day", but dysphemism is number 10 on Merriam-Webster's list of "10 Fancy Words for Fancy Talk".

Inflammatory.

Definition 2 (especially of speech or writing) arousing or intended to arouse angry or violent feelings.

"inflammatory slogans"

synonyms: provocative, incendiary, inflaming, inciting, agitating, stirring, rousing, provoking, fomenting, rabble-rousing, seditious, subversive, mutinous;

Perhaps it is melodramatic language.

M-W:

melodramatic adjective

: emotional in a way that is very extreme or exaggerated : extremely dramatic or emotional

Sensationalizing

Simple Definition of sensationalize : to describe or show something in a way that makes it seem more shocking than it really is Source: Merriam-Webster's Learner's Dictionary

Perhaps you are just looking for the verb "to color" in the sense of writing using a biased language in order to manipulate the readers' opinion, i.e. to propagandize.