The guy is a smug asshole. A smug asshole does not listen to the
  customer. He believes he knows better.

  He may be more logical, but his beliefs are getting in the way
  of any logic he may possess.

  Humility is a crucial factor in logic - [1]Seedy Johnson ? - if
  you're smug, you've lost before you begin.

  Self-confidence is one thing. You need self-confidence.
  But "I already know more" before you even hear what the other
  person knows? That's arrogance and it's bad for business, any
  business.

References

  Visible links
  1. https://www.facebook.com/seedyjohnson?hc_location=ufi