Is it her voice or does she just come off as annoying?

I just watched The Crazies again and I can't blame the deputy wanting to shoot her because she won't shut up. She did the same thing in Pitch Black. I can't figure out if it's just her voice that grates the nerves, or her attitude or maybe it's just the scripts she gets. She's ok starting out but the moment she tries to act bossy, yikes!