Manners generally are pleasant and can create a sense of ease. Manners can also be a warning that something unpleasant is about to happen.
Yesterday I was leaving the grocery store. I got to the door as three extremely large guys walked shoulder to shoulder into the store. I backed up my cart because they had no intention of allowing me out the door before them. One of the guys after passing me turned his head, while walking away said "Excuse me ma'am." The perception was what I noticed, and the intent. Their body language did not match the congeniality. The group of guys didn't look friendly. If I saw them walking toward me in the parking lot. I would have definitely taken a different path to avoid them. Maybe you earn street cred each time (you think)
you've convinced someone you're civil while being ironic. Keeping the options
open to look like a doe eyed fawn, or a psychotic killer.
"Goddamn it I said excuse me." said while checking for dirt under the fingernails, after responding to a text message that caused you to bump into the person in front of you. As a side note, if they had any respect for you as a person they would have noticed you were distracted and gotten out of your way.