The rule of thumb that seems to be in place is that once a pot gets actually pushed to a player (not just that it is in front of him, but he has scooped it in and taken possession) the house will not take it back from him. I don't know if this is a written rule, a legal requirement or just the the way things seem to be done. That being said if a casino makes a habit of paying a player who has the winning hand but doesn't correct the error until after the pot gets pushed then the house is inviting players to take a free shot at them, because a player no longer has any incentive to correct the error at a time where it can be corrected easily.

That being said I don't object to paying a player in some situations.