I used to interview people - mainly teachers - for jobs. One of my own mentors in this role was the managing director of a large company who attended interviews for new staff. As the candidates arrived on the company premises he met them in the guise of the caretaker, key chain, overalls and all. He noted their attitude to him in what they perceived to be his lowly position, and compared it with their demeanour when introduced to him a second time in the boardroom.
I was once shown round a hospice by the chaplain. I had agreed to cover for him at holiday time. I noticed that whilst he couldn't wait to introduce me personally and politely to the consultant, medical and nursing staff on duty, he walked past the cleaners without so much as a greeting.
I'm particularly sensitive about this - probably because my dad was a caretaker. He took good care of me.