Samsung had a zero dead pixel policy for a while, but withdrew it. I don't know who else, if anyone, has one now.
So, unless there is a zero dead pixel policy or the dead pixels are *obviously* too many or *enough* of them in bad places, it seems companies apply their own dead pixel policy in a subjective manner. You might just have to take your chances.
Odds of getting one with zero dead pixels are pretty good, though. I've got 9 LCDs around here. Two have one dead or stuck pixel and the others have none.