Here are my thoughts:

(1) A lot of airlines, hotels and car rental company agents are not well versed in the rules. Often I find myself ignoring them when they explain false rules, or trying (not always with sucess) to explain the correct rules to them. This is extremely frustrating.

(2) There are a lot of jerks out there who expect more than they deserve. It's great to get an upgrade, but if one isn't available or you aren't guaranteed it (by the rules), you have no right to complain. There are plenty of jerks who want what's way above and beyond of the rules and reason. Take the jerk who's sitting in coach, but expects first class type service (like having the FAs hang up his coat in the FC closet) because he "spends a lot of money with this airline" or "usually flies in first."

The other component of (2) is how it relates to (1). Too many agents don't know the rules, and people become used to getting stuff they don't deserve. Then they demand it when they finally come across someone who knows what they're talking about.

d