Another large part of the reason is that I'm naturally too empiricist. I don't have any confidence at all in the sorts of generalizations that make first-impression categories meaningful. Ask me if rich people are greedy, or college professors are snobs, or people who didn't go to college are dumb, and I'll most likely respond with a brief synopsis of the people I know who fit into the category followed by a caution that of course my sample space is too small to draw any generalizations, so I really guess the answer is that I wouldn't hazard a guess.
But I do have one category that I can drop someone into with a few minutes of conversation. I call it the "used-car salesman" category because the first time I consciously recognized the type as a type, the individual in question was a used car salesman. Also, it fit the common stereotype. Of course I wouldn't hazard a guess as to whether the stereotype is actually typical of used-car salesmen, and I can quite confidently say that most of the people I have put in the category had other professions.
A better way to explain the category is that I get the impression that the person I'm talking to is not thinking of me as another person, valuable in myself, but as a resource to exploit, a possible means to achieving some goal. As Kant said, the person is viewing me as a means rather than and end.
Now, of course we are all guilty of doing this from time to time, viewing other people as a means rather than an end. But for some people I get an impression that this is their habitual form of behavior. That they never, or almost never, view any person in any other way. That they are, in short, sociopaths. Those are the people I call the "used-car salesman type".
I can't explain what it is that gives me this impression. I don't have any strong evidence that this impression corresponds to reality. Yet, it is a strong belief when I have it, and I'm not likely to ever trust a person that gives me this impression. I get the impression rarely, but more often than one would like, assuming that I do have the faculty of identifying sociopaths almost by sight. An unlikely claim, I know, yet an unshakeable conviction.
That's the impression I always got from Bill Clinton. I can't say why. I can't even prove that it's a fair impression, but it's one that I'm not likely to give up. So that's why I found this note by John Derbyshire so interesting:
... From the time I first set eyes on Clinton, I knew this was a guy I would not trust to mail a letter -- just an obvious liar and fudger, ... Yet people still tell me -- a conservative acquaintance told me just yesterday -- "you have to see past the charm..." No, I don't. What charm? I am, always have been, and always will be, utterly uncharmed by Clinton. He's just an awful person, a nasty person, who treats other people abominably. And it's obvious. Isn't it? ...I can't speak to the charm part. I've never been charmed by any politician so I just assume I'm not a representative case. But that part about it being just obvious that Clinton is a scoundrel --yeah. It is obvious. How could anyone listen to the man for ten minutes and not know it?
I know I'm appealing to a fundamentally nonrational intuition but, well, I think I'm right. And the Derb backs me up.