"...because their work is good, and because they're easy to get along with, and because they deliver the work on time. And you don't even need all three. Two out of three is fine.
"People will tolerate how unpleasant you are if your work is good and you deliver it on time.
"People will forgive the lateness of your work if it's good and they like you.
"And you don't have to be as good as everyone else if you're on time and it's always a pleasure to hear from you.