I personally best like characters who are entirely unsympathetic jerks. *shrugs* Or at least deeply flawed. (This is why I tend to like villains better than heroes.)

Now I think it depends on the story - you can push this too far - but I can definitely get into a story where basically everyone is a selfish jerk. And I think that a lot of people can, too.

I mean, think of how well Scarlett O'Hara is. And basically she's a cold blooded, calculating bitch who spends an entire novel trying to steal someone else's husband. She gets married to three other guys, but only for money/out of spite (stealing one of them from her own sister, another from a friend), doesn't even like her own children, and sees nothing wrong with using prisoners as free slave labor (and horribly mistreating them). And yet she's loved. So I figure that using her as an example, you can write a real monster well and still have him/her be wildly popular.