Rating is very unreliable and should not be taken seriously.
Regarding god and bad moves it is in most cases reliable. But it doesn't understand that the best move is the move that gets the best result. So often another move is better in practice as it makes the winning or draw more easy or complicated for a human.
How reliable is the chess computer in giving you a rating and telling you which moves are good or bad? It seems to me, the computer sometimes is very unreliable.