Continuing my theme about dealer mistakes. What do you do when you spot another player being paid in error?

I know for sure I would not say a word and believe most other players would do the same.
However, the other night another player really annoyed me when pointing out the blundering dealer's mistake as he was about to pay me on a losing doubled bet of 40.
Now, I subscribe to the unwritten players' code that if a casino wants to pay you some money you should take it. It's tough enough to win as it is and you have to take anything extra that adds to your ev.
There's absolutely no reason to feel guilty about it as the casino has plenty of unethical practices aimed at relieving you of your money and make plenty of mistakes against the player that are not picked up.