I myself would let the child know that is not right to sass off to an adult and that they need to realize how they are acting is inappropriate.

I believe in the 1-2-3 rule. When my 6-year-old is not doing what she is supposed to be doing, I start with "1" then "2" then she races over and does what is asked. It's actually quite magical. Every once in a while she'll ask what it was that she would have lost at 3, but not often.

I no longer do the warning thing. It just leaves me with a kid who's a brat until he thinks he'll be punished. Instead, I model the behavior I want my child to use in his own relationships: when he is bothering me to the point where I don't want him around me anymore, I tell him so and ask him to leave.

If I ask him to do something and he does it, but in the rudest way possible (e.g. the kid says in a snide voice, "There! I took out the trash! Happy now?"), I completely mis-perceive the snotty comment and reply with a sincere, "Thanks! Really appreciate it."

When he realizes that he's not pushing my buttons with his behavior, he gives it up pretty quickly. That's good for him and for me.

What happened to just sending a kid to his or her room? When I was little and was sassy or naughty, off to the room I was sent.

Ha. But now that I think about it. I didn't have a TV, video games, a cell phone, etc. I had my stuffed animals. And they were unsympathetic to my pouty face.

I agree with Brad. Also, you really have to focus on behaviors, not "attitude". Attitude is closely tied to feelings. You can't judge or criticize people's feelings, kid or not. If you're expecting your kids to happily do everything you want them to, look at yourself. You don't and no one does. Poor responses from kids are best ignored if they're minor and if can't be ignored you should give the kid a chance to "try again". Always, always remember that you are the adult.