Would you want to hire someone who trashed her former employer? As the next and future employer, you might be concerned about your own reputation should bad blood come between you and the new hire.
No matter how much you hated your old boss or loathe your current supervisor, it is a BAD idea to let anyone interviewing you know about it.
Instead, try to put the situation in the best possible light if pressed and avoid discussing it if possible. Negativity can only hurt you, so why go there?