Hmm. Default is off, except for one of my players, in which case it's on.
Unfair? Not really. See, 3 of my players are powergamers wannabe. By that, I mean they -try- to be powergamers, but aren't really good at it. Still, sometimes they might stumble upon something, so I still review -everything- they want to use, even WotC stuff that isn't core.
The fourth player I have uses stuff from everywhere. Stuff from the Net, from various books, whatever. -But- everything he goes for make sense, and actually is usually very underpowered, actually. So I let him do whatever, with the obvious caveat that if he'd try to do something crazy, I'd nix it.