Are you AWARE of your own Truth-Default, which is your tendency to trust a stranger?
It's been studied and sociologically proven that "the majority of people believe most people are mostly honest most of the time."
Chinese people naturally default-to-skepticism toward people they don't know (陌生人 mòshēng rén), not just foreigners, because by definition, they only care about the level of Guanxi.
Default-to-skepticism is how they think, but you wouldn’t know it by how they behave, as every gesture of friendliness or goodwill is for the sake of developing/deepening Guanxi, while in a literal sense there isn’t any ‘trust’ as we understand its meaning in the West behind their passion and camaraderie.