Posted By:
davidcyclebackConcerning the sellers in the group, it would have to be fairly simple.
99.9 percent of bad sellers are either incompetent (can't tell a 1952 Topps and a 1952 Topps reprint, think a Mint card can't have 6 creases) or unethical.
Sellers in the group would have to be competent (consistently correctly identify and describe the stuff they are selling) and agree to follow ethical standards that bad sellers don't follow. It could be as simple as that.
Along with reputation and recommendations, it would be simple to review a seller's auctions to judge whether he is competent and fair at describing the items he sells.