Almost all my past jobs were customer service related. (retail sales, hotel desk & reservations, and customer service for a printing company)

I try to be really nice to the people on the other end of the phone cause it used to be me.

Never attribute to malice that which can be adequately explained by stupidity.
(attributed to
Robert J. Hanlon)

People with true credibility and integrity don't need to tell other people how great they are. They also don't need to belittle other people to feel superior.
(msmith)