I've mentioned in previous posts that facilitation plays an important role in product management. I will go further now and venture that facilitation is the single most important skill that a product manager must possess.
When a product manager visits a prospective customer and conducts a one-on-one interview, you strive to understand the prospect's situation and problems. You must facilitate the prospect to obtain this understanding. You have to listen, but you can't just capture a laundry list of grievances. No, you actually help her think of all the important facets of her situation and get to the root issues that affect her.
The best way to measure your effectiveness is not by gauging how much you have learned, but by how much the prospect has learned. You've used the Socratic method to teach the prospect.