I'd like to suggest that within forums where trades occur that the first post where people list critical information about a trade such as within the actual Diablo trading sections that it always remain editable, that way when you sell an item you can remove it from the original list. That way spam about wanting to buy the same item would be reduced and people don't need to go searching through a thread to find out what current offers on items are and what has sold already.
Thanks for reading :]