yes. I think we should not leave behind any records.
I ran into issues with a tickets test because it was trying to display some tickets another test left behind. I had stubbed User.find for the one ticket i was using in the test. But ticket.commenters crashed for the other tickets because User.find had not been stubbed for that id.
So my preference would be to clean up after tests and be able to assume the test db is empty when writing a test.