There are indeed many search results on Daring Fireball for “jackass”, but I regret almost none of them. I’ve used the word very deliberately, and I hope consistently, to describe people who are, in fact, jackasses. To call a jackass a jackass may be impolite, but it is not inaccurate or unfair.
The whole piece is great, but I had to quote this part.
I once got in trouble in high school for calling a teacher a jackass in class. My mother had to come in early the next morning for us to have a “conference” with him. After meeting him, she said that I shouldn’t have said it in class, but she agreed with me. I received no further punishment for that one.