Yes, I understand letting a wine breathe. I get wine from an award winning home winemaker. Since it costs me nothing, the Merlot above was going to be used for cooking. I always take a sip at opening to ensure it didn't go bad or have cork rot. The flavor was not vinegar, but more like mouth-puckering fruit rind that had been soaked in grape juice. I put a vacuum wine stopper in it, pumped out the air, and stuck it in the fridge to decide what to do with it.
Two days later I needed fridge space and decided to dump the wine. We wash the empty bottles, remove the label, and return them to the winemaker for sterilization and reuse.
I took a sip standing at the sink and couldn't believe it was the same wine! Rich, fruity, smooth and delicious. I generally let reds breathe for up to 24 hours, but I've NEVER experienced a change in flavor like this bottle offered. Any ideas why?