All these screwed up bullets were taken from dead animals, mind you.
But these are not the norm.
I can not see how a bullet taken from a dead animal could be thought of as a screw up, unless it was hit by a truck after a less than lethal shot

If by screw up you mean, too much meat damage and not enough penetration, knowing the strength and weakness of an individual bullet and bullet placement will help. All bullets may fail under certain conditions. Many seem to be a compromise between adequate penetration and adequate expansion. Knowing which of these two properties they favor will help in bullet selection and should be kept in mind for bullet placement.