While air fryers are versatile and can cook a variety of foods, there are some foods that may not be suitable or yield optimal results. Foods with a high moisture content, like fresh fruits or leafy greens, are not recommended for air frying as they can become limp or lose their texture. Lightweight foods like spinach or leafy items may also fly up into the heating element. That's because it's so light and air fryers circulate air, so without weight it's hard for very light items to stay put in the air fryer basket. Additionally, foods coated in wet batter may not crisp up well, as batter can slip off before it cooks. It's also important to avoid putting items wrapped in plastic or with non-air fryer safe materials into the appliance. It's always best to consult the specific recommendations and guidelines provided by the air fryer manufacturer for the best cooking practices and safety precautions.