Yes, if you are nice, your relationship has better chances of success. Not being mean or hurtful with your words... Thinking about the impact on your audience...
Years ago, a gentleman summed up an hour session with, "So, I gotta be nice to my wife?"
"I think that is worth a try," I responded.
6 months later he called me and said, "I tried that being nice. It worked."
He was not a man of many words. He liked simple and straightforward. He thought it made sense to be nice and was worth experimenting with it. It worked.