In my experience, that means you are quiet. When I was in High School, girls said that they liked talking to me. Why? Because I didn't say anything back. If they got to know me, they would know I was an *******, and kind of a **** as well. However, because they could vent all of their bullshit teen problems on me and I acted like I payed attention, it means I was good to talk to. It never got me layed, but at least it killed some time.