The [f..] last story of the iteration

I hate the last story in a Scrum iteration. If we are about to finish it, we sacrifice quality to fit it into the iteration. If it's not completed and carried over, either it's finished in the first day (best scenario, but stays the whole iteration there cluttering the task board...) or expands in a crazy way (2 hours in the last day of the sprint easily become 16 hours in the next iteration!!). WTF.