[swhipple]

That the Earth's average temperature has been rising is also not untrue and can also be observed and measured. Yet it is often denied in political context, e.g. Sen. Jim Inhofe brought a snowball into the Senate as evidence to the contrary.

"The sky is blue" is a non-political statement only because no one stands to make money convincing people otherwise.

[noobermin]

I kind of lumped "non-propaganda" with "demonstrably true" which you are right about. A true statement becomes propaganda when spoken at certain times especially when communicated while omitting related details. I think the general point still applies, it isn't binary, some statements aren't propaganda at all, while some have some mixed in, and some are fully propaganda. On the continuum, I'd rate the statements under consideration from least propaganda-ish to most as

   "sky is blue" < "here's a snowball"
                 < "avg temperature of Earth's surface is rising"
                 ~ "${average_comment_on_HN}"
                 << "This snowball demonstrates climate change is a hoax"
                 < "${fake_news_articles}"

Is is fair to put "${random_comments_on_HN}" in the same category as "${fake_news_articles}" because they are both "propaganda?" No.