A cucumber that feels mushy or squishy to the touch is probably rotten and needs to be thrown away. Likewise, the cucumber should be replaced with fresh ones if it develops any mold, which is a sign that it has gone bad. Cucumbers that have grown yellow, brown, or dark stains on their skin should not be eaten since they are spoiled.
It's crucial to remember that not all visual or tactile changes are a sign of rotting and can instead result from natural ripening. However, it's always advisable to stay cautious and toss a cucumber if you doubt its safety to reduce the possibility of contracting food illness.