Years ago I finished what I started no matter if I liked it or not. Because of that I have 3 of the ugliest quilts in the closet in The Box That Shall Never Be Opened.
Now, if I don't like how something is progressing I stop and re-evaluate. If it's truly bad I take it apart and add the cut pieces to my scrap box. If it's re-workable, I'll play around with it until I like it. Life's too short to deal with something I don't like and probably never will.