A bullshitter does not primarily care whether what he says is true or false. His primary goal is to win votes, sell the car, get applause, make the teacher think he has read the paper he was supposed to read, generate buzz, or something of the sort. Bullshit is a sort of consequentialism in action (not that all consequentialism is bullshit, of course). If I don't know what I'm talking about (I haven't read the book, say) then I might sincerely hope that what I say is true, but first and foremost my concern is with appearing in a way that gets others to do what I want them to do. I am pretending.
Whenever anyone does anything they try to do it well, or properly, or at least adequately. Otherwise they are not really doing that thing but something else, such as pretending to do that thing or trying to make it look as though they have done that thing. If I mow the lawn and don't try to do even an adequate job then I am really just trying to pacify someone else (my neighbors, my wife, perhaps even my conscience), not to mow the lawn. I am making a show of mowing the lawn. And I will, in that case, care about putting on at least an adequate show.
Internal to everything we do is some sense of adequacy, if not goodness. We live by standards. We cannot do otherwise, but we also cannot live by standards while sincerely affirming that any standard whatsoever is just as good as any other. This would be one possible reason to deny that relativism exists at all. It's an impossible position to hold, so why bother trying to counter it? I agree that it is impossible to hold, in a way that is similar to the impossibility of thinking nonsense, but people still do utter (and 'think') nonsense. And I think they do fall into relativism, even of the very crude sort discussed in textbooks.
Moral relativism typically shows up in the form of someone saying "it's all relative" when a discussion of ethics gets difficult (socially, intellectually, or in some other way). It's a way to disengage so as to avoid hurt feelings or hard work or boredom or whatever. Aesthetic relativism shows up when students treat artworks as something like bullshit, as content-irrelevant shows whose value is only to produce a certain effect. I once had a discussion with students who claimed not to care at all what the critical response had been to a movie. That is, they claimed it made no difference whatsoever to whether they would watch a movie if critics had universally praised or panned it. Of course they might have been exaggerating, but I think at least some of them really meant it. They had found no correlation at all between movies that get good reviews and movies that they enjoyed. (If you never read reviews this is hardly surprising, I suppose.) Their faculty for enjoying higher pleasures of the movie variety was seemingly non-existent.
There's a similar indifference to content in the way many students talk about responding to poetry. To hear them tell it, a typical essay about poetry is all bullshit. This probably is an exaggeration, and probably not exclusive to essays about poetry--minimum length requirements on any essay encourage bullshit, whatever compensating virtues they might have. But I bet most English professors encounter at least some bullshit when grading essays on poetry, and I expect there is more of it when it comes to poetry than in essays on, say, history or engineering where one can fall back on mindlessly listing facts. And it's not just students. Very large numbers of people, I think, really have no response to artworks beyond thumbs up or thumbs down.
That might be going too far, but I don't think it's going much too far. And so far as it is true, people can't be articulate about art because they have nothing to articulate. (Anything they do 'articulate' will be bullshit.) And then standards will be invisible to them.
I had a point but I seem to have lost sight of it. One (boring) thing I want to say is that relativism is bullshit, in its crudest form it's simply impossible to believe or to mean. The possibly less boring thing I wanted to say is that bullshit is produced by people who care about effects and appearances, not content, and that relativism about aesthetic matters encourages the production of bullshit. If you don't believe that there is a difference between good art and bad--that the only relevant differences are between what is liked and what is disliked--then you won't try to produce good art (or good criticism), just popular art (or criticism). And something similar goes for ethics. As far as you think of your own ethics as just a product of your culture or genes or upbringing, etc., you will take an external kind of view of them, as if they are just part of a chain of cause and effect, and not something whose contents can be evaluated. This is not a position you can actually live in, but it is possible to insist on talking as if it were.
(I'm not sure that I am not confused about this, but when I started to write this post--several days ago--I felt as though I had an insight to share. I'm posting it now for whatever it might be worth.)