To assume that because we like or dislike something, that is the same thing as it being good or bad.
First, there is a substantial difference between the subjective and objective responses. For instance, I don't care for Picasso. Never have, much. And I'm not a big fan of abstract art. I like art to have people in it: recognizable people. In fact, my favorite artists are the Pre-Raphaelites, they of the garish colors and Arthurian legends and odd personal relationships. But this isn't because the Pre-Raphaelites were better artists than, say, Picasso, Monet, Renoir, Rembrant and just about anybody else out there. My subjective response is personal, a pure, unrepentant enjoyment of Victorian Art. My objective response is that the Pre-Raphaelites were really pretty awful.
But the subjective and objective responses aren't always so obvious. I think they get confounded due to (1) social opinion; (2) our awareness of an objective standard. We feel compelled to give reasons for not liking things. Or for liking things. We justify our stance, illustrate that our reactions are not simply personal prejudice. (The only art where personal reaction is allowable, if not preferable, seems to be food, although I have eaten with people who have educated palates.) I loathe the book Anthem, and, moreover, I could make a fairly good case for it being an intrinsically worthless book. My subjective response doesn't disappear, but it is morphed into a desire to show that my response is worthwhile.
Along these lines, a professor of mine once claimed that Americans are natural film critics because we are accustomed to automatically weighing our reactions against social opinion and other movies we have seen (and we see so many). That is, we develop, almost by default, an objective standard. Movie-watching becomes an exercise in balancing the subjective and objective reactions. I didn't like this, and this is why.
Where the process fails is when we lose sight of our own subjectivity. The whole 70s relativity movement took this too far by insisting that worth is merely a product of environmental factors; that is, Shakespeare only lasted because white, educated men promoted him as a classic. (A rather pointless argument since it still doesn't explain why white, educated men picked Shakespeare over, say, Bob Jones from Brighton.) Subjectivity isn't useful as a scholarship tool. It is useful because it keeps us humble. It reminds us that our personal biases may be at work and that feeling really, really strongly about something isn't automatically the same thing as being right.
This confusion of the strongly felt subjective opinion with the objective view surfaces when you are talking to people who get all bent out of shape about Clarence Thomas but extol Bill Clinton, with a shrug of the shoulders over his particular pecadillos. I hear it in my office from people who "hate" Bush and Condoleezza Rice (no, I don't know why) and, for that matter, any Republican but praise to the skies the equally human, and equally flawed, Democratic contenders. (To say that I distrust the people in my office on political issues would be an understatement.) It crops up in my college with students who want to replace the bad, evil narratives of the 19th century with the correct, good narratives of the 21st century. It's a kind of Descartes approach to the world: I think, therefore I must be right.
All this leads us to:
Tendency the Second
The belief that people who disagree with us are bad and people who agree with us are good.
Naturally, this is a harder tendency both to prevent and to argue with. It arises, originally, simply, out of communal living. When a number of same-thinking, same voting, same believing people gather into one place, they begin to think that all (right-thinking) people think and vote and believe the same as them. Afterall, it's what they see and what they know. It's what they experience. The opposition becomes foreign, bizarre, wrong-headed and morally corrupt. At the risk of illustrating my own biases, this type of parochialism crops up with liberals and right-wing fundamentalists.
The difference between parochial liberals and parochial right-wing fundamentalists is that right-wing fundamentalists often have a theological reason for thinking that the opposition is wrong-headed and morally corrupt. That is, they fall back on a supposed objective standard, which, if they are moderately honest, they will compare themselves to as well. Which doesn't prevent them from being narrow-minded, pig-headed and self-righteous. But honestly narrow-minded, pig-headed and self-righteous.
Liberals of this ilk, however, have a harder time since the basis for their disgust is nothing more or less than a subjective response. I don't like your opinion, therefore you stink. I have a different opinion, therefore I do not stink. I may sound the same as you, talk the same, be as belligerent, obnoxious, in-your-face and close-minded, but I'm not the same as you because I don't think the same things.
It's the difference between judging by behavior and judging by the quality of one's soul. Ironic that religious people should depend more on the first these days and fundamentalist liberals should depend so much on the second.
The other side-effect to all this parochial subjectivity, other than a bizarre reliance on conspiracy theories, is a rejection of human fallibility and incompetence. All mistakes must be the result of deliberate malfeasance (or sin, depending on one's bent). The problem with this approach is that ambiguities, paradoxes and discrepancies become a stumbling block to understanding (no, they don't need to be) and learning, for that matter. We spend a great deal of time in my grad classes being perplexed and startled and shocked by the oddities of history. In one class last semester, the students were discussing the essays of a Native American, William Apess, who makes the argument, somewhat belligerently, that he is a better Christian than the white so-called Christians who raised him. Members of the class mused, "Well, how could he even be a Christian if the people who raised him were so mean?"
It's the "subjective experience rules all subsequent decisions" theory of the universe. I give these discussions a wide berth since I'm afraid I'll start saying things like, "What--you were born yesterday?" Or "How dumb do you have to be to be admitted into grad school?"
Perhaps, I am being harsh, but I would assume that by the time we reach graduate school, age (if not experience) would have taught us that a gap exists between our experience, our ideal and our day-to-day practice. The struggle to comprehend that gap is part of being human. The acceptance of it is a mark of maturity. That is, no theory, principle, religion, ideology, government or institution functions at its ideal. None. Welcome to Reality 101. We all deal with this failure in different ways. We don't always deal with it as well as we would like. And we don't always keep the subjective and objective separate. But only the totally subjective will believe that their sacred cows and pet ideologies are free of this disparity while everyone else's falter in the trough of corruptness.