Tough topic this because apart from a small taste at a meeting, the only person who drinks your homebrew is usually yourself so it's not usually a case we can pinpoint on particular example.
I have never had to dump a batch. I did have one called wheaty goodness which got a little infection and was iffy when freshly tapped (keg) but after a few weeks in the fridge it mellowed out and became a beautiful Berlinnerweisse like beer.