Cauliflower may develop small brown or black spots due to oxidation or the beginnings of mould. If the spots are minimal, you can cut them off and the cauliflower is still safe to eat. However, if the browning is extensive, or if the cauliflower has a strong unpleasant smell or a slimy texture, it's best to err on the side of caution and discard it, as these are signs of spoilage and potential bacterial growth.