Two bad interviews stick out in my mind: 1) Early in my career, I interviewed with a large multinational automaker for an entry-level position. I had ~1 year of professional experience. They did something ridiculous like 4 interviews over the course of 6 months, each time telling me they were "close" to a decision, then a month or 2 later calling me back for another interview. I needed the interview practice and the job was interesting, so I kept going. After the 4th I interview, they told me they went with someone who had 5 years experience.

In my youthful ignorance, I sent the HR contact a polite email explaining that they were not very respectful of their candidate's time and if they intended to fill an entry level position with an experienced engineer, they could've cut me loose after the first interview. Surprisingly, the HR contact called me up 6 months later and asked if I would like to interview for another opening in the same dept. I said no thanks. My guess is the original engineer quit.

2) Later in my career I interviewed with for a business/project management type position to see if wanted to take my career in that direction. The direct manager was kind of rude and condescending throughout the interview. She complained about her own boss, rolled her eyes at me when I replied I couldn't start for 6 weeks, and when I asked about career paths she replied there really wasn't any and this job was it. I didn't get the job, but that was a blessing....