Anyone who has spent time levelling in the Barrens knows the bad side of general chat. In the worst cases it is a black hole of intelligence and social graces. Because of the anonymity of the Internet (and because it is a lower level zone with a high population) people don't seem to want to be polite, kind, or just not blatantly racist/sexist/intolerant. I have not been to the Barrens where there has been any intelligent conversation going on, and frankly, I'm glad Blizzard is destroying the zone in the next expansion.
The world trade channel is also less than helpful. Getting an honest answer out of it is like getting blood out of a turnip. Occasionally you can even get some trading done...but don't count on it. People simply don't regularly use this as a trade channel, but instead use it for wide-area chatting (because it is available throughout all major cities). If there were a global chat channel, trade might actually be used for trading.
What this says about our MMORPG society: Essentially, nothing. People have needs and they will use the tools available to them to satiate those needs (i.e. using trade as a general chat channel). People will also act however they want without any constraints if in an environment where they are not held responsible. The Barrens, being a low-level high population zone is filled with people you will probably never have to deal with again. You don't *have* to be polite with them because you don't need them.
Sadly, this isn't enlightening at all, nor is there really any way to control this. Guess we all just have to deal with it.