Interesting article. Short and to the point. Especially last part. In all books I read about sales was something opposite: Never let your client know if you don’t know something. I read many main sales books and in all of them there was one main theme: Lie, lie lie. Do whatever you can just to sell product. I was disgusted by them. I stop reading them and instead I started using my own personal skills I learned over my life. And… I succeeded!
I have one gold rule (among few more): Never lie to customer. If I don’t know the answer, I say: My apologies. Honestly I don’t know answer to this question but I will check it for you and get back to you via email. Can I get your email, please? — Always works — and I get their email too.