If the helper is doing from the heart, she is a performer and you dont worry that she will take up bad practice. This is something related to her mentality and attitude to work.
My first bun bun was very good. Her performance didnt deteriorate till the last day. She knew the things of the bad helpers too but never adopt any. Then come a half day worker (very efficient and clean on household cleaning but didnt want to go market and follow recipes on dishes other than steaming), talking on the phone, watching DVD nightime till 2am and taking nap in the afternoon. Now have a 2-3 months tourist going back home soon.