I had a similar discussion with a friend recently... Myself, I usually trust implicitly, until there arises a reason for me not to trust suddenly. This has got me burned in the past before, but I've also seen it inspire honourable behaviour in others. (That is, they're surprised at my trust and work harder to keep their end of the bargain because they don't want to disappoint me.)

And you're right about the small things... I remember feeling quite ashamed when someone pointed out that, here in Brazil, everyone complains about corruption in politics (and truly, it is crazy) but then they go and print a fake university enrolment form in order to get half-price at the cinema... I was doing this, and stopped immediately.

Ultimately though, I always refer back to Stephen Pinker's research... The world is a better place to live in now that it has ever been, and becoming even better year by year. And it is because of you, and people like you... The altruists of the world, combined with the ease of communication... Spreading and inspiring good behaviour in others. I only wish I could live longer than my allotted ~80 years to see where we end up in 500-100 years...