When hummus has spoiled and reached the point of no return, it's obvious. You can tell when your hummus is bad because it will have a rotten odor and look moldy. If you're not sure if your hummus has gone bad, simply open the container and give it a sniff - if you don't like what you smell, then get rid of that dip! If you're feeling brave, you can taste a little bit of the hummus - it will taste sour and off. When in doubt, it's best to throw it out!