I think trust/mistrust is on a spectrum and it depends on where you start. I think people tend to go forward and backward on the spectrum even with those we are closest to. I think because people are human there is no such thing as perfect , complete, continuous trust . (I hope someone can argue that point because I don't want it to be true.)
Here's a web site I found that looks really good:

http://www.coping.org/growth/trust.htm