I think Red Panda is on to something with her levels of trust.

1.Things I'll talk with anyone. And things that seem personal that don't really matter to me anymore so I can share them.

2.Things things that aren't currently an issue but can be issues. Share this when starting or trying to trust someone.

3. Things I'm probably not going to share at all and will only share if I DO trust someone.

Having levels of trust shows strong boundaries. There are those who trust no one and on the other side there are those that freely share anything. Are trusting none and sharing with all can be a sign of being fearful of relationships. If you trust no one, then you are without a sounding board or someone to turn to in a crisis.

The one that shares all could be fearful as well. There is generally a way to share something and still hold out on the most intimate portions. Perhaps putting all their "stuff" right out there will let them see who turns away from a "mess". Putting it all out there is a screening for friends. If they can't handle it, then you know there will be no friendship there. If they seem supportive, then perhaps friendship will develop.

I also think that in most cases a friendship develops and as it does trust grows.