I'm so new to quilting that most of these looked just fine to me (gulp!).
One of them mentioned puckered binding. It made me race to check the table runner I did in my beginner's quilting class. I can proudly say my binding isn't puckered, no matter what-all else is wrong with it. (And there's plenty wrong, from the chubby binding mitered corners to a bow-legged sashing, to widow's peaks on my quilt-stitch corners.)