We were both working at a university's IT department as your basic go-to people for teachers and students. He seemed to rate everyone's intelligence and general competence at life by how much they know about computers, and didn't bother to hide it with customers. I overheard his side of a couple phone conversations with one teacher who was new to computers and needed a lot of help, and I could just hear the contempt dripping from his voice when he spoke with her. When she complained about him, he proceeded to let the other workers in our office know that she was a troublemaker, stubborn, etc. Eventually when she called the IT desk and got him she would ask to be transferred to another person, and he would refuse. Other people started avoiding helping her based on how much he complained about her.
One slow day at work the phone rang and I saw it was her (we had caller ID for teachers' offices) so I picked up quickly before he could, and ended up walking her through a fairly complex installation process over the phone. It took about thirty minutes and she was very patient and good-humored, an ideal customer. When I was done the other guy directed his contempt at *me*, I guess for not treating her like an idiot. The help desk was really dead at that time of day and there were no other customers I could have been helping, so the long phone time was really no problem.
As a former IT worker, I have to say the biggest problem IT workers tend to have is looking down on customers for not being computer-savvy. You don't expect auto mechanics to sigh and roll their eyes if you don't know basic car stuff, so get off your high horse, folks.