Unqualified, uncaring, socially inept bosses. A few lazy, incompetent or manipulative coworkers. Oh, since this is a rant thread...hahaha, I had a coworker, Mr. X, who was the laziest, most incompetent and the least intelligent person I have ever flown with. I joked that, over three years, he improved so much, that it got down to once a flight did I think he was going to kill me. 100% of the time he would get his position from a fix incorrect. If we were east, he'd say west. Then, he had a 100% success rate in screwing up every tasking that he had. He would sit there, texting his son while I did all of the preflight requirements...and he was junior. Whenever he got into a jam, he'd freeze up and I'd correct it. I told our boss that his performance appraisal should just say "Alice will fix it."

Anyhow, that's one rant. :P