kala,
Ususally, bun's English is not bad especially under 30 yrs. I can say my new bun's English is quite good. Understandable & easy to communicate. But her pronunciation is not accurate, with typical Phillipine accent. But it is fine to me because I will teach bb myself.
My bun's English is terribly bad, and difficult to communicate, but her overall performance is good, such as taking care of children, cleaning and cooking. That's why I'll keep her, and I'm going to renew the contract with her.