In my experience the DMs and players are of vital importance to the fun you will get from a game. In many cases they are more important then the scenarios. That is true for standard campaign, but even more so for Living Greyhawk. Remember that the scenarios are written so that they can be finished in a 4 hour slot and that they need to be fun for the biggest group of people. Most scenarios will be pretty generic and apparently combat orientated. The scenarios leave a lot open to the DMs to get the most out of a scenario especially role-playing wise. I have talked with people complaining loudly about a scenario. After having listened to them, I could in many cases point out that many of the worst points of complaining had to do with the DM and the fellow players.
People should also realize that this is a world wide campaign. There is no more administration with LG as with a standard campaign, except that in a standard campaign most that work is done either by the DM or one player. You have NO idea how many cheaters are out there... and even one cheater can ruin the fun totally of other players.
Running a game at a convention which needs to be finished in 4 hours is a skill in itself. Which scenes do you rush on and which scenes the players have the time to role-play? It never hurts to talk with people before hand about what kind of gaming they prefer. In our region we allow the players to make their own tables before we start moving around a bit to get the average levels on a more equal level. Hence most people will be playing at a table with people with a more or less similar gaming style.
Complaints about differences in treasure between the various regions are weird since the guidelines for treasures and the current rules concerning buying items place this on one line worldwide. In my experience players also expand way too many resources during even the most basic scenarios. What is wrong with sleeping between combats? I pointed this out to a friend of mine who was making the same complaints and he looked at his expenditures and he did realize he used way too many scrolls and potions.
For example: I recently heard of a module in which a poor beggar asks the party to take a month-long sea journey for basically no reward.
Are you honestly telling me that ANY DM would offer that up to his own group? That he wouldn't expect them to tell the begger to shove it, even if the group contained a paladin?
Remember that one of the assumptions in Living Greyhawk is that people play heroic PCs, something that is stated within the rules. If you create a character that does not fullfill this criterea you will need to take a closer look at the blurbs before deciding to play a particular game with that character. Besides, in the end you will always be rewarded.
Anyway, some of the best LG slots I have run btw where with the scenarios with the worst reputation. I had superb players and I was willing to go beyond what was written down litterally and the result where some great games.
P.S. As for the a scenario giving more xp if the players opted for a side track, that is not entirely within the writing guidelines for LG. When you don't like a particular session, ask for the scenario, so that you can judge where the fault lay. Whatever the reason, send a mail to the local triad so that they can learn from it. If people do not send in their complaints about an adventure (and make them as specific as possible) then there is no way the Triad can make the scenarios more fun for others involved.