It seems that people in general (and especially the gaming subculture) have a sense of entitlement. Why? I don't know exactly, but it seems to be that because the customer has the money, the company is supposed to bend over backwards and kiss their behinds to get it.
Maybe this is just my observation, but it seems like we can be better customers some times. The talk radio channel I listen to was going on about customer service yesterday, so I've been mulling this over for a while- many of the customer service horror stories seem to boil down to people either making really dumb mistakes or just flat-out being jerks and expecting companies to accomodate them.
I realize that people I buy stuff from have mortgages to pay, groceries to buy, and gas tanks to fill. The vast majority of companies want you happy, because happy customers buy more stuff (or at least don't bitch about what you did wrong). If you're cool to customer service people, they're usually extremely cool to you in return.
Now beyond these generalities, gamers have alot of special considerations. Most gamers are literate, educated, detail-oriented, smarter-than-the-average-bear types. It's also one of the very few industries where the consumers make at least as much of their own content as they buy from professionals. Could you imagine video game fans making their own games? Or movie fans making their own movies? Sure, it happens, but not on the scale and level of quality that gamers make their own adventures and source material. I can understand having high expectations, but the fact is, alot of gaming material isn't made for great DMs. They don't need it. More of it is made for novice or time-strapped DMs, and sometimes it shows. Many DMs take this as condescension or "dumbing down" the game.