Tell Or Not Tell?

Should I or should I not? I saw that leech trying to sell a product which the cost is more than the price that he is selling!! It is ridiculous to sell a product where the cost is greater than the selling price right? I am sure that he did not even do his homework despite me telling him so many times that he need to check the weight and the packaging of the item before calculating and determine the cost of the item. Well, I think its better for him to buying silver online than to sell thing online! He is just plain stupid!