This is an extension or inspiration of @Prof. Song's "what intps don't say" thread.
What can a person say to you that will instantly lose your respect?
I'll go first, mine is "Hi, how are you?"
Okay fine, mine actually are:
"He's not attractive so he doesn't have an excuse to be arrogant"
"he/she doesn't act like a normal guy/girl"
"I don't understand how people who can't articulate in class do well on exams, this shows how unfair the exams are"