Only real thing that bugs me with the mb is people not understanding selling in bulk vs individual or smaller stacks and cause prices to needlessly drop. Some people need a stack of 99 items and list at lower per unit price, but much higher total price. Other people need only a stack of 10, 5, or 1. For these people they can pay a higher unit price but lower total cost. There is no reason for someone listing a single item to compete with the stack 99 unit price and then undercut them.
Also, wth hell is with undercut for first sell when items are listed in different cities? Depending what region you buy in it may be cheaper to buy the "higher" priced item after SE takes tax.