To all of you who are reaching this blog while searching for "when onions go bad" or "do onions go bad" or "what do I do with bad onions," I have a picture of an anthropomorphized onion in the archives, which means that you've been misled. Until now.
Do onions go bad? Yes! They sprout and rot. My model for the deco page pictured in this post? It had sprouted and when I picked it up to dump it it was mushy. It's now where stuff from green bins is processed.
What do you do with onions that have gone bad? I'd recommend composting them, dumping them in your green bin, or dumping them in the garbage. In that order.
There's nothing below the fold.