Wet cat food should not be left out at room temperature for more than 2 hours. Bacteria can grow rapidly in moist environments, leading to potential spoilage and causing stomach upset or illness in your cat if consumed. It's best to discard any uneaten wet cat food after this time frame to ensure your cat's health and safety. If it's very hot (above 90°F/32°C), the food can spoil even faster, so it's essential to be more cautious in such conditions.