I remember a former co-worker whom I thought was being rude exclusively to me. She was the receptionist at my then employer and would get into bad moods and slam down my mail on my desk. I asked her if she could please place it on my desk more quietly and she responded “Lalala” with her fingers in her ears like a little kid trying to tune out his parents. I tried to rise above it and ignored her for a while, hoping she would knock it off, but she didn't stop. I didn't see her treating anyone else like that so I finally went to her boss, the office manager, asked for a private meeting, and told him I was having a problem with the receptionist.

To my surprise, he told me that everyone else in the company had complained about the receptionist too. She was eventually fired. We all liked her replacement.