Does apple cider go bad

If you push it too far.

Apple cider vinegar, is Apple cider that has already 'gone bad' and since vinegar in itself is a preservative, it is not possible for it to become 'out of date' or 'go off'. The worst that can happen is it may lose some flavour over time.

I have been using a huge 4 liter container of Apple cider vinegar that I have had for over 3 years, it still tastes wonderfull, and I have never had any problems with it.

So in essence, no Apple Cider vinegar cannot go bad.