De confianza

Mexico is what you might call a low-trust society. People you already know are valued highly, whereas strangers are inherently suspect. This might explain why the expression ser de confianza is so frequently heard.

• ¿Es de confianza? How well do you know him? Can he be trusted ? For example, to keep a secret.
• Es de muchísima confianza. He's someone I've known for a long time. I trust him completely. He won't steal everything from my apartment while I'm on on vacation.

Other verbs are possible with confianza as well:

• ¿Le tienes confianza? Do you trust her?
• Ándale. ¿O qué? Ya no me tienes confianza? You don't trust me anymore?
• No me da confianza. I don't trust her. She hasn't earned my trust. She feels untrustworthy to me.

If you want trustworthy in the sense of 'reliable' or 'dependable', go with responsable.

Confianzudo

Confianza is about being in the inner circle of trust. Perdóname la confianza pero ... Forgive me being too forward or for assuming that we have a closer relationship than we actually do, but ...

Confianzudo describes someone who tries to gain your confidence quickly by oversharing or assuming a level of confianza that has not yet been earned in the relationship.

A person who is desconfiado is naturally suspicious and untrusting.

Confiar

Confiar often means to trust someone in the sense of believing them.

• Deberías de confiar más en mí. You should trust me more, believe what I say.
• No confío mucho en los bancos. I don't trust banks (to not steal my money).
• Confío en tu palabra. If you tell me you'll do something, I believe it.

Con toda confianza

Con toda confianza is something that sales people say. Con toda confianza. Go ahead, try out the mattress. Lie down on it. Ya iba a cerrar pero si quieres algo, con toda confianza. I was just about to close, but if you need something, just let me know. You can ask without commitment.

Si estoy interrumpiendo algo, con toda confianza díganmelo. If I'm interrupting, just tell me. Don't be shy. Go ahead. (telenovela dialogue)