12. Talking negatively about past employers
Redditor Alienthere says if someone talks badly about a previous boss, then he won't hire them because they're usually people who "struggle with authority or dealing with coworkers."
A few examples of the inappropriate comments that candidates have made during an interview include "my manager was incompetent," "my boss played favorites," "my boss wouldn't give me the days off I requested," or "there was a lot of drama with coworkers."
These complaints may sound tame, but they still constitute as bad-mouthing past employers, which is the ultimate professional faux-pas.