Does salsa go bad if left out overnight?

Yes, salsa can go bad if left out overnight, particularly if it contains perishable ingredients like tomatoes, onions, or cilantro. Bacteria can grow rapidly at room temperature, increasing the risk of foodborne illness. It's best to refrigerate salsa after serving and discard any that has been left out for more than two hours. If in doubt, it's safer to err on the side of caution and throw it away.