1) It should be evident within the filtered items if I have already sent a message for a product, because when I click "send message," the previous message isn't loaded. This results in sending two different messages for the same product.
2) If there's a flagging feature within the filtered items, we can make better reviews. For instance, if I don't like a product, I'd want it either not to appear in the filtered item list or to be tagged for removal. At least then, I could skip the product without delving into its details.