A few observations :
1) On the 'agent' & 'principal' bit in the case of revenge chapter, I think that the reason why people would direct their revenge towards 'principals' even though it is their 'agents' that are at fault, could very well be that the 'principals' are thought to deserve punishment for employing those 'agents' in the first place. The 'rationale' could be "If you didn't hire these people, then I wouldn't be unhappy and therefore, would not feel the need to punish you."
2) Coming from an advertising background, I now know why some form of advertising can become blind spots. In the chapter on adaptation, because of our ability to adapt, it can cause us to, over time, pay less and less attention to things around us, which for me includes advertising, which would then render such things as unnoticeable. So note to self, do not come up with advertising that stays the same for a long period. Must vary.