Funny that you wrote about listening skills in sales -I just answered in a job interview to a question "Describe good salesman" that the key is to listen to peoples needs; not only what they say their looking for but to read between the lines by trying to connect with them so that they will feel comfortable.
I think listening skills are probably the most important of all social skills and everyone should focus on enhancing them. Friendships and relationships can get deeper and better if one truly listens to another.

This post was really interesting in my point of view since I'm studying education in uni and very interested in all psychological and social aspects of humanity. Thank you for writing this good quality post!