"On Bullshit" is a well-known essay by philosopher Harry G. Frankfurt. Princeton University Press for some reason published it as a tiny book, but you can enter the title into your favorite Internet search engine and find a free PDF. It's only about 20 pages if you care to read.
But you don't have to. Frankfurt's basic concept is that the difference between lying and bullshit begins with recognizing that a liar knowingly utters (in speech or writing) falsehood. Being aware of the difference between truth and fiction and concerned that the audience may detect deception, the liar must use artifice to align his or her representation with facts otherwise known. In this way, the liar pays honor to truth.
In contrast the bullshitter does not care about truth. He (most likely) may not even know it. A common occasion for bullshit is ignorance. The bullshitter just says whatever is useful, whether to make himself appear not to be ignorant or for some further end. But the bullshitter may also know on some level that his representations are false. It just doesn't matter. He makes no attempt to align his bullshit with evidence because he presumes that his audience doesn't care either, or won't be bothered to investigate. This is what is really happening with what the Washington Post fact checkers label as Donald Trump's 15 daily lies. They are actually bullshit. Does he believe that his inaugural crowd was the biggest ever, that there were 3 million fraudulent votes cast for Hillary Clinton, or that climate change is a hoax perpetrated by the Chinese? It doesn't matter. Truth is irrelevant to him.
I maintain, however, that there is another form of bullshit, in which the bullshit assertion is literally true. The bullshit lies in representing or implying that the literally true assertion has some significance or meaning that it does not. A good example is
this purported "fact check" about Adam Schiff, which the Bullshitter-in-Chief's cultists think is somehow of great significance and somehow discredits or deligitimizes the House investigation into the BiC's treasonous behavior.
Schiff told reporters that "We [meaning the House Judiciary Committee] have not spoken directly with the whistleblower." The purported "fact check" is that the whistleblower had in fact communicated with a member of the committee staff who told him to get a lawyer and file a complaint with the Inspector General. That's it. Now, I personally think that Schiff's statement was literally true: no member of the Judiciary Committee had then, or has now, spoken directly with the whistleblower, and Schiff was not aware of the person's identity. But so what? This does not matter at all, it has no bearing on the salient facts of the matter nor does it impugn any of the evidence ultimately provided to the committee or to the public.
But this is now a very common tactic of bullshitters. Make people waste their time with irrelevant distractions, pretending that they are somehow important, and getting reporters to go down those rabbit holes which, as we see, they are entirely eager to do. That was actually the basic use of the stolen DNC e-mails. There was nothing of importance in them, but they nevertheless sucked up half of the verbiage in the New York Times.
So I resolve, as a New Year's resolution, not to waste my time with any form of bullshit.
And let me just add, I have been accused of only publishing comments I agree with. This is false as one can readily determine empirically if one has been reading. I frequently publish comments with which I do not agree, and often respond to them, or leave it to others to do so. What I do not publish are comments which are inane, offensive, or as I now understand, bullshit. As I say, I will not waste my time with it.
Also, too believe me, I am perfectly capable of rebutting every idiotic comment. As I say, I just can't be bothered to waste my time. I prefer to engage in intelligent discourse. And bullshit is perfectly easy to recognize if you want to. That's part of it's essence -- it's intended for the benefit of people who don't give any more of a shit about the truth than the bullshitter.