Trusting people is my default setting. I trust them unless I sense a red flag not to trust them.

For example, in two places (Morocco and Tunisia), random guys who introduced themselves to me told me within minutes of our conversing with each other, "You can trust me."

I immediately felt that there was something off about each of these guys. If there were ever a red flag, it would be a random guy trying to reassure me upon first meeting that I could trust him. In each case, I stayed for a few moments to chat amicably with the guy and then bade them farewell.