I have to say, I don't hate Zoey at all--I think she's pretty awesome.
But as far as her not so awesome advice that she gives Dawn, I think that Zoey is very much like a replacement for Johanna now that Dawn is travelling around without her. Now, I don't mean a literal replacement, but it just strikes me funny that Dawn puts so much store by not only what her mother thinks of her, but what Zoey thinks of her, too. Its almost as if she left home only to have a reminder of her mother there to try and give her advice, only its in the form of a rival. And not to mention the fact that Zoey has a Glameow, just like Johanna does.
I might be reading too much into that, or I might just be insane, but either way, that's why I think Zoey comes across as biotchy to a lot of people, because she tends to almost scold Dawn sometimes when she tries to give her advice.