Reply To: Washing Disposable Cups

You can always explain to them that the designers of this product focused on the cost of manufacturing rather than reusability, conequently there are crevices that cannot be washed leading to bacteria growth. You could go a step further and show examples of reusable plasticware, these are generally made from harder plastics to prevent absorbtion of food and lack crevices that cannot be cleaned out (althouth they are often treated as disposable).