When its passed down to someone who's asian.
I don't quite understand it but after tons of experiences with trying to be nice to someone who's Asian. They're totally ungrateful.
For example, I was driving yesterday and I came to an intersection where I had to yield onto this busy main road. I was pretty sure i was going to be waiting for quite some time. Only a few seconds into my wait, A man driving a Ford pick up slows down and lets me in. I gave him the "Thanks" wave and started feeling good that someone was nice enough to slow down and let me in.
A few minutes later, I see someone uphead who is in the same ordeal i was in earlier. I slow down to let the person in [Asian] and he looks at me like "WTF" he finally hesitates for a second and goes onto the road. I wait and wait. No "thanks" wave. I forget the ordeal and continue driving with him in front of me.
We come to a red light and Theres this subway restaurant off on the right side of the street with someone trying to get out. Guess who decides to block the intersection. Yup you guessed it.
This is just one out of many examples, but the most common is driving courtesy.
My conclusion, If you see someone Asian is waiting to get let in onto a busy high way or something of that nature. Don't waste your efforts. It will all end on him/her.