The agency always claims that they will provide certain weeks of training to the helpers before they came to HK and once they arrived, the maid will have certain training lessons.
I have the same experience as you around 3 years ago. At that time, I employed a one never worked in overseas, but worked in Philippines as domestic helper.
When she came, she work very slow & quite "知 ching". Though she is 29, she looked very tried everyday. At that time, I only have a 2 years old girl & a couple.
Later, she also told me she got homesick & need to go home ASAP. She just worked only a month. You see, I waited her for over 3 months .... I am really in a very bad situation at that time.
So, I will never employ a one never worked overseas.