Is it in the culture? Questions of behavior and idea promotion

When did certain behaviors become widely pardonable as "we shouldn't, but we do anyway"? 

Why did explanations like "we are imperfect" and "we are only human" become acceptable excuses for some behaviors but not for others?

Who decided that product advertising should lure people in by appealing to negative base instincts instead of luring people in by making them think they were achieving something positive? What's the difference? Are we not just talking about what desire impulse to tease here?

Why is what's "cool" so often depicted in an appeal to the former instinct, not the latter?

Why are we as humans such impulse junkies to begin with?

Why is doing the right thing what so often leads to one being used and seen by others as being weak? Why are we so apt to take advantage of and dump on each other within this perceived hierarchy?

Why do we consider temptation so difficult to harness in some regards but not others? 

If looks spark initial attraction, when and why did society determine what is desirable, particularly if many of these features have absolutely no utility?