It's like having 5 people leaving a building, the first holds the door for the second, the second for the third, the third for the fourth, but the fourth looks at the fifth with a sneer and decides to let the door shut on them instead of holding the door open like everyone else. You can probably imagine the fifth person would think that the fourth is an asshole. Nobody has to do anything for anyone at the end of the day, which I understand, nobody owes me any favors. Looking back at it, that's what really pissed me off, the ugly look they unnecessarily gave me when I politely smiled at them.