I had an absolutely awful boss, who did the minimum possible amount of work. When it came time for the yearly performance review, he photocopied my previous review, for a DIFFERENT JOB, crossed off the parts that didn't apply to the new job, and rated me poorly, with no supporting evidence. He did this to another person who transferred into the department with me, too. As soon as we got a new manager, I demanded a reassessment of my performance. A few months later, our company had a massive headcount reduction. The woman who transferred in with me (and hadn't demanded a reassessment) got laid off. If I hadn't boosted my performance score by getting reassessed, I'd have been laid off, too.