Trusting Others

Main Question
How do you know when you can trust other people?

Reason For Question
I've had a few major situations where I trusted somebody and they broke my trust. For example, I recently read a spirituality book called, Where Are You Going? by guru, Swami Muktananda. I read the book in one day and found it extremely motivational. In fact, I thought it was one of the most impactful books I ever read. Then, I start doing some due diligence to be safe and type, 'Swami Muktananda criticism', into Google. Lo and behold, I find a lot of articles and stories from people that were close to him talking about various acts of violence he encouraged and sexual abuse he participated in. In fact, there was even a New Yorker article on it in 1994.

Sub Questions

1. If somebody betrays us, should we trust them again? If so, when?
   
2. If somebody lies to or misleads us, should we distrust all of their past and future statements? What if the person has been helpful in the past?
   
3. What are the best indicators that you can trust somebody? gut feeling? testimonials from others? congruence?
   
4. Is it better to be trusting first or to be critical first and make people really earn your trust?