That depends entirely on your level of satisfaction with the transaction. You are rating the other person's actions, so don't hold them responsible for problems that are out of their control (items damaged in transit, you end up not liking the scent of the FO you purchased, etc). Even transactions for which there are problems can result in positive ratings if the other person handles the problems well. Use this as a guide:
= Very Satisfactory
= Satisfactory
= Neutral
= Unsatisfactory
= Very Unsatisfactory