General, vague rejection letters. Please, if you are ever in charge of writing a rejection letter to someone, be specific. Tell them exactly what it is that is wrong with them, why they're not good enough. Be extremely detailed. Because trust me, it is far worse to get one of those horrible, vague, obviously form rejection letters that gives you absolutely no reason at all for why you didn't get the job. Because then you are forced to go over your resume or your cover letter or your interview a million times and wonder what you did wrong.