Unsympathetic Characters

I am reading a book now that got all the right reviews and caused a bit of a stir in the more literary corners of the book world when it came out in 2006. Its author is an extremely talented writer, and the book is very clever, but I don’t think I am going to finish it. I don’t like the characters enough to spend more time with them. I don’t like the main characters, and none of the secondary characters are compelling either. I don’t care if they show some sort of growth over the course of the book, or if they just remain in their mean little worlds. Even the cute little kid is whiney and I want him to shut up. There is a skill in making characters so believably irritating that readers want to avoid them…but it may not be the most useful skill.
I am trying to understand why I am reacting this way; why unsympathetic characters are such a turn-off (this isn’t the first book I have put down for this reason) because at the same time, there is nothing I like less than the overly-perfect hero, the kind whom the author demands we love before he has earned it from us by what he does on the page. For the second novel I wrote, I took the most unsympathetic character from the first and tried to figure out why she was so horrible. So it is not that I don’t like edge and ambiguity.
I think that maybe what I am missing from these books is a sense of humour, or, better, a sense of humility (which is the necessary prerequisite for humour). When I speak of a sense of humour, I am not talking about the ability to tell or laugh at jokes. I am speaking of an awareness of the absurdity of the world that prevents us from taking ourselves too seriously. It is something like what Dean Priest says to Emily in Emily Climbs:

A woman who has a sense of humour possesses no refuge from the merciless truth about herself. She cannot think herself misunderstood. She cannot revel in self-pity. She cannot comfortably damn anyone who differs from her. No, Emily, the woman with a sense of humour isn’t to be envied.

Those who can take refuge from the merciless truth about themselves, who think themselves misunderstood, and wallow in self-pity are, frankly, kind of boring. And the characters in the book I am reading take themselves so, so very seriously.
I think, by contrast, of the sort of characters Arthur Phillips writes about. Most of them are fairly unsympathetic in the same way as the ones in my discarded books — they are selfish and self-centred, venal and shallow. But humour pervades the novels, gently poking and prodding the characters, the author, and the readers. The characters are nothing if not ridiculous, and that makes me care what happens to them.