Emulator

1. If it's checked, clear the "Enable Cheats" checkbox in Config -> General.
2. Right-click -> Properties on a game, tab to AR Codes, enable some cheats there, close the properties window.
3. Launch the game.

Since "Enable Cheats" is disabled, none of the enabled cheats work. This is not a problem by itself, but if you don't realize this global "Enable Cheats" checkbox exists in the first place, you'll spend several minutes wondering why the cheats aren't working, if your game version matches the cheats, that kinda stuff. Which is obviously not ideal from a usability perspective: You did just specifically enabled cheats in the Properties window, you wouldn't expect to be a second option somewhere entirely different that you'll also have to enable, without anything to indicate that!

There should be some kind of information somewhere to inform the user that cheats are globally disabled when he enables them. The first thing I can come up with is put a Warning message on the Properties -> AR Codes page when Enable Cheats is off, but if someone can come up with something better, feel free to suggest it.