Robb is a dick to Theon (I think thats his name...the non-Stark kid banging the red head hooker), and both he and Bran are shits to the old woman looking after Bran. Jon has been a dick, but you are right in the fact he seems to learn his lesson from it. Sansa is Sansa. All these kids seem to take after their mother, more than Ned. Lady Stark is HORRIBLE to Jon, as I'm thinking of his good bye scene with Bran while he was in his coma. Even Arya has her little snotty moments, but she's too damn awesome to hold it against her. Ned isn't afraid to throw his weight around, but only seems to do so when necessary or he feels his family is threatened. I don't think the kids are demons by any means, but they all seem fairly arrogant.
Robb was mean to Tyrion because he suspected that he had something to do with Bran's assassination attempt, so of course he was not going to be pleasant toward him. Jon (being a bastard child and all) naturally act like he has a grudge against other people, but he has became alot better since then. Sansa...well, she was taught to become a fair lady who aspired to marry to the most powerful man in the kingdom and to bore him lots of sons, and Joffrey (despite his dickish personality) is the heir of the throne, so combine that with her age you get someone like Sansa. Bran is young and became a cripple, who once aspired to become a Kingsguard, so of course he'll be sulking and in foul mood. I don't think any of their children, except for maybe Sansa, is intolerable.