This sounds like the agent is biased, not necessarily the helpers he/she represents. Is the agent local Chinese? There are alot of biases against Indians and other ethnic minorities in HK. (I say that, a bit shame-faced, as a local myself. I don't hold those views, but I know others who do). That said, there are also agents who will badmouth mainlanders or other groups -- just alot of stereotyping.
And sometimes that trickles down to helpers, who are so terrified that they will be mistreated or underpaid here. And many of them have never worked in a multicultural city like HK before.
I think most helpers just want a decent employer regardless of skin color. My Filipina helper's friend loves her Indian employers, who are strictly vegetarian. That's why she gets a food allowance, cooks her own food, and also has long lunch breaks. My neighbors are Indian, too, and they seem to get along just fine with their helper.
I've gotten 2 great helpers over the years from Arrow Agency, run by two Americans in Kowloon. They would never say anything like that. They're decent folk who seem to personally know the women they represnt - maybe not the cheapest in town. But when you are hiring someone to be in your home all day, you want to spend a little more to make sure things go well.
Arrow Employment Services
Ask for Allan or Ione, a husband and wife team. Their great assistant is named Swannie.
Good luck! And remember that, while there are some bad apples in HK (particularly helper and property agents) most people are pretty decent here.