system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do wine “spoil” so quickly after being opened as opposed to hard liquor?

You can put the cork back in and put it in the fridge, but the flavor is never the same, and sometimes it spoils and tastes unpleasant overnight.

So what makes hard liquor so resilient to time and exposure compared to wine?
gpt
Others pointed out the wine oxidizes, but they missed the main thing: 

There are air-breathing bacteria that can survive a moderate alcohol content, turning the stuff into acetic acid (aka vinegar). The way they used to make vinegar was to just take wine, cider, beer or any other alcoholic beverage, and let it sit in an open vessel, so that bacteria from the environment would infect it and turn acohol into acid. 

So when you open a bottle of wine, the exact same thing is going to happen. Oxygen and bacteria get into the bottle, and start producing acetic acid. 

Hard liquor doesn't do that because it has a too high alcohol content for bacteria to live in, although some can survive in a dormant form - alcohol for disinfection has a much higher alcohol content than the usual 40%.