I hired an Indonesian helper years ago. She's efficient but not a good caretaker. She argued with my daugter (aged 5) with childish wording and made naughty face to each othe all the time (she was the one who cried at the end). She only played with my son (aged 2) because he wouldn't fight back to her. No sense of danger: when I was doing revision with my daughter inside the bedroom, she took a bath and left my son alone in the sitting room. I told her it's very dangerous. She said no problem, my son was watching TV so it isn't dangerous. I terminated her finally.
A good helper will not let the kids do whatever they want and will explain (not argue) to them when they are wrong. Of course it's hard to find and depends on luck.