The 'back and forth' criteria that Dottie mentions is interesting----particularly the fact that the topic doesn't really matter.   I guess what must matter is a 'mutual curiosity'.   

It's a nice add on to Eliza's point from From: Jun 14 - 10:45 AM...she said "I tend to draw people out and get them talking about their life, hopes and/or troubles". And that nearly everything they say is interesting to her.