Yes, I can confirm that about Hong Kong and I don't condone it. They are not a homeless shelter.

I know they don't like it if people adopt a sleeping posture, e.g. by laying on your arms. I was never so tired that I had to that.

I always ordered something. In fact, sitting there quietly with a tray in front of me is to their advantage: I was well groomed. It reinforces the impression that they are popular.