Actually, she goes snarky no matter how you treat her over the course of the game.

As an aside: How come no one cares about the Yuffster like this? I've seen just as horrible things said about her, too, but no one either seems to care, either in the echoing or the defending. My guess is because she isn't regarded as a 'serious' opponent for Cloud's affection, which is where I think a LOT of the hostility towards both Tifa and Aerith comes from.