I would absolutely not get a pup from a breeding where either parent was less than "fair." From a "fair" dam or sire I'd like to see some mitigating factor as well, like if they had a history of producing "good" or "excellent" pups in previous breedings.
Just getting a good OFA score isn't enough to make a dog worth breeding, though. It's more of a potential disqualifier than a potential qualifier, if that makes sense. Same things with eyes, heart, etc. - don't breed a dog that doesn't pass, but don't breed a dog just because it DOES pass the exams, either. For me temperament and ability are the really important things.