I rarely have problems with the moderation system. And let's remember: when Matt set IHub up, the idea of a panel of unpaid mods was a fairly new concept. I remember writing a critical and pretty sarcastic post about it a SI.
But it was a success. And it's still a good idea, because it saves tons of money, and that's important for a site without the resources of an X. Yes, there are some bad mods, but not all that many.