How to be effective by having no agenda

I enjoy meeting all kinds of people and it’s easy for me to talk with people without an agenda. I love to get to know people by sharing our stories with each other, talking about what we’re working on, and explore how to help one another in life. But, I have to confess, I get easily confused about these “networking” opportunities, when I read tweets like these:

The best way to convince people you don’t have an agenda is to not have an agenda.” — Kip Jacob via @Qideas

It’s great to have good friends who truly love me and don’t have an agenda.” — @JanPlansATL
I’m good at not having an agenda, being sincere, unassuming, and helpful. But maybe there’s more to the story, or there’s too much to explain that doesn’t fit into a tweet, because just having no agenda doesn’t quite work in cultivating business as a consultant or salesman, does it? I’m confused, when the tweets above are contrasted with these tips for success::

via 3 Powerful Skills You Must Have to Succeed in Sales

Listening sincerely and without an agenda. The buying process is not about you and your wants and needs, it is about the customer. Too many of us come to the sales table with our own agenda. We are sometimes too busy thinking about quotas, promotions and commissions. It’s not about us, it’s about the wants, needs and expectations of the prospective buyer.

A sales person with an agenda tends to push too hard and often doesn’t listen well. Leave your agenda at home.

Huh? How can a sales person close a sale if s/he doesn’t have a desire to make a sale, thus an agenda? I get that listening well and explaining how a product/service fits the customer needs is a good thing, but that sounds like an agenda to me, because a competitor’s product/service might fit better during that conversation. Does a good sales person without an agenda tell the truth and honesty refer the competitor, rather than manipulate the conversation to sell the product/service that’d earn him/her commission?

via book description for The Hidden Agenda: A Proven Way to Win Business and Create a Following by Kevin Allen —

Each of us pitches ideas every day. Sometimes we sell our ideas to a small room full of skeptical colleagues. Sometimes we pitch to a boss, or a board of directors, a new organization, or for the contract of our dreams. Regardless, it all boils down to the act of stirring someone to join you—to agree to follow you. Yet we consistently underestimate how critical it is to recognize the needs, spoken and unspoken, of the decision maker. Decisions are made by people, and people have needs and agendas. Understanding these needs and agendas are critical to success in business. Kevin Allen’s approach is not about persuading, but about creating a connection that assures a mutual win.

So do I need to have an agenda or not? Or are there different rules when it’s about friendship vs. work in the marketplace? Help a brother out, help me understand, please, thank you.