1;
I don't know whether I'm trustworthy or not. It depends on who you ask. Trust me unconditionally without knowing me, and I'm likely to rip you off. Get under my skin and my trustworthiness is absolute and predictable. When approaching that point, I change in the way I let people trust me - in a good way. Then, I refuse to let myself be put in a position where I'd be trusted with more than I can handle. If you shove it down my throat after I've tried to refuse, the results can be horrible, but by then you should know to trust me when I tell you not to push it.
2:
I can trust others with my life. But few get to see what moves deep inside my head. It's a calculated risk, if I were to avoid trusting anyone with more than the simplest trivialities, my probability of finding happiness approaches zero, fast.
Do I trust others easily? No. Superficially, yes - it might look that way.
True trust takes years to develop, and seconds to break. I take chances, in the hope that I made the right choice in trusting the people I trust. Only time can tell. Only time can heal the wounds when I trusted the wrong person.
3:
that which is true is a good basis for trust. But it's not always enough - sometimes when relying on someone's trust it's done in a way to trick a person into impossible dilemmas. Predictability is more important than having everything rooted in the truth. I'd rather have someone who answers truthfully 95% of the time, and refuses to answer 5% of the time over someone who answers truthfully 95% of the time, and tries to tell me what I want to hear 5% of the time, but both are ok as long as it's predictable.
No matter how much of my trust you've earned, I aim to be predictable. Providing real consequences help make me predictable in trivial matters. The emotional consequences are enough for someone I share a mutual feeling of trust with.
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The other answers in the thread are interesting. Even though the questions are simple, the answers reveal a lot. I find both funny and sad answers. Which is which, I guess depends on who views them, but yes - there's many "right" ways to look at this, and only one common factor , predictability. I don't mind people who I can't trust, who don't trust anyone - they're predictable enough to just scream no when you need someone you can trust. No uncertainty, no problems which deciding if trusting someone is even an option.