"I once showed up for an interview and the manager wasn't there that day. No one called me to let me know.

The assistant manager was not apologetic for the scheduling issue at all. She was literally just like "oh, she's not here today" in a tone that suggested I should somehow already know that. She said they would call me to reschedule some time the next week. I told her I was currently unavailable M-W but could come in any time Th-F. She said if I couldn't make time for the interview, I probably wouldn't be a good fit. I said okay, and went on to my other interviews and ending up working elsewhere.

You'd think that would be the end of it, but both the manager and the assistant manager badmouthed me to a few other people in the industry, including one of my friends.

Hello? I made time for an interview. You disrespected me by not calling me to let me know it was canceled. I gave you the times I was available to reschedule, and that was disrespectful somehow?"