FrogReaver
The most respectful and polite poster ever
It goes against the rules in the game. "Ignoring the rules of the game" is a way to play, but I wouldn't claim that it's valid.
If you want the PCs to know or find something, then the world should be constructed in such a way that the check is not uncertain. Because if it is uncertain - if the DC is more than one point higher than the relevant check bonus - then we have rules for resolving that.
I think the most valid interpretation is that no content exists in reality until the DM describes it to the players. So unless he's retconning something he's told the players then it's not cheating.
It mostly sounds like it's just not your desired playstyle.