Every job I've left, I've left clean. I give real notice, hand things over properly, and say goodbye to people the right way. Years later those old bosses still take my call and those doors stay open. It's served me well, though sometimes I wonder if I ever left a place saying what I actually thought.
More people experience this than they realize.
You leave every job with your reputation and relationships intact, and doors that stay open.
If this sounds familiar, the Library can help you find the bigger picture.