Thanks stawka, reading that it looks like there are 3 issues that currently acrue defects.

1) cancelling a sale due to item being out of stock, or sold to another buyer

2) Not resolving a problem in the resolution centre and the buyer asks ebay to step in. Ebay finds in buyers favour. ( only 2 allowed in 12 month period )

3) Late shipment defects. ( 5% allowed for top rated sellers, 10% allowed for others )