Lots of people are tossing around the word. Apparently with no regard for what it actually means.
So what is propaganda? Well according to Merriam-Webster:
pro·pa·gan·da
noun ˌprä-pə-ˈgan-də, ˌprō-\
Definition of PROPAGANDA
1
capitalized : a congregation of the Roman curia having jurisdiction over missionary territories and related institutions
2
: the spreading of ideas, information, or rumor for the purpose of helping or injuring an institution, a cause, or a person
3
: ideas, facts, or allegations spread deliberately to further one's cause or to damage an opposing cause; also : a public action having such an effect
— pro·pa·gan·dist noun or adjective
— pro·pa·gan·dis·tic adjective
— pro·pa·gan·dis·ti·cal·ly adverb
Since the term isn't being used in the context of Catholicism we can disregard the first.
What's clear from the applicable definitions is that propaganda isn't a synonym for lies or falsehoods. It is, in fact, a politically, ethically and morally neutral term. Propaganda can be either true or false. Legitimate or illegitimate. It is defined not by its content but by its polemical intent. Essentially, it simply means that someone is trying to convince you of something.
Equally clear from the above is that the term is being regularly misused and abused on this site. In diaries and in comment threads we see it put forward as an epithet to de-legitimize opposing arguments and views. This, strictly speaking, is nothing more than arguing that a particular advocacy or criticism is invalid simply because it is an advocacy or criticism.
A secondary misconstruction argues that propaganda is illegitimate because of its source. That is; that an argument is invalid because it consists of "talking points" being deployed by some entity with a vested interest in the issue. Examples of this are Government propaganda, Radical propaganda, Right wing propaganda, Left wing propaganda, Corporate propaganda, etc.
This is itself a form of Ad Hominem argument known as the Ad Hominem circumstantial. as well as an exercise in the Fallacy of Irrelevance known as the Genetic fallacy.
What it all boils down to is that anyone making an argument either for or against something is engaged in an exercise in "propaganda". The only substantive distinction to be made is between the factual or nonfactual character of such arguments.
Denouncing something as being "propaganda" is nothing more than fallacious rhetorical posturing, serving no purpose other than to avoid engaging arguments on their merits. Anyone who practices the fallacies described above shouldn't be surprised if they are hit by a wave of criticism. They have no one to blame but themselves.