In Of Mice and Men there is a lot of isolation. Multiple characters seek out someone who they can talk to who actually care or even just listen. For example Crooks the black stable hand just wanted someone to talk to. He lived by himself and nobody respected him because he is black and has a messed up back. When Lennie came in to Crookses room he was aggressive at first, but quickly warmed up to him and started talking about his deep thoughts. The same thing goes with Curley's wife. She was just dying to talk to anyone. She seemed like a flirt and she probably was, but I am sure that if she just had someone to talk to and who cared she wouldn't be such a looloo and the end of the story would be different.
A good listener will listen and care. They will listen and not just think about themselves, but think about things you didn't think of. With a good listener you don't have to worry about them running their mouth. I am very fortunate to not have confided in someone and them tell everyone. I have had people confide in me before and I have valued their friendship more afterwords. There is some sort respect for someone who has put their trust in you.