Once, at my first job, the CEO of the company sent a group email in which he essentially lambasted my ability to do my job.

I wasn't even hired as a programmer, I was a data entry guy who learned how to code on the job, and at this point I was literally the only person writing code for the company. I regularly worked 12+ hours every day, and even though I had to learn practically everything on my own I was still getting things done -- at least, I would have gotten things done if the CEO didn't keep pulling me off of my projects to work on whatever his latest ultra-important-idea-of-the-week was. I was even working for an 8 hr/day, 5 day/week salary, putting in extra hours for free.

But no, my sacrifices and hard work weren't good enough in the CEO's eyes, and he chose to say that to multiple people in an email, including investors in our startup. I don't remember exactly what was said, but whatever it was made me so livid I couldn't do any work; every time I sat down to code, I thought about that email and it so infuriated me that I couldn't concentrate. It took me twelve hours just to calm down enough to get back to coding.

After that, I refused to communicate with the CEO except through my boss, the CTO.