I did it twice in Indonesia - I trusted and liked 2 people immediately by their faces.
The first person I trusted and liked immediately was my supervisor - and this turned out to be a good judgement call as he turned out to be a very kind and welcoming man. Why did I trust him? I will never tell him this, but it's because his face reminded me of the kind happy indonesian gym instructors that were all around me when I was younger and my mother used to spend most of her time at the gym.
The second person I trusted and liked straightaway was a man I interviewed at my first village - who I had been warned may be garrulous due to his dissenting view of the company. But as soon as I saw his face I immedately said to myself "that is a kind man", and he turned out very courteous and happy to explain his thoughts, though politely, on the company. Of course I only met him for a couple hours so I don't know whether he really is a kind man or not. I don't know whose face his reminded me of, but it must've been someone kind from my childhood.
I know it's wrong to trust people by their faces, but I couldn't help it with these two.