Most people think that IT folks are too arrogant and should be more like doctors, lawyers and mechanics.
The problem in IT with clients it twofold -- they either unwilling to think or they think they know more than they actually do.
The first type of clients are completely oblivious to basic concept that explain simple matters becomes the laborious equivalent of explaining Heisenberg Uncertainty Principle to the average 7 year old. If you work in a modern office and cannot master basics of MS word, you should not work in an office. Nothing will drive an systems engineer or programmer crazier than dealing with people that you have explain simple (I mean really simple) concepts over and over again. Imagine a dentist having to explain flossing to a grown man every appointment, or your mechanic explaining why you should change your oil over and over again.
The other group are even more dangerous -- the know it all. Few Doctors should have to put up with patients telling them how to administer medicine because they saw a Cialis commercial. Lawyers don't tolerate morons thinking they can do a better job at defending themselves from a few episodes of Law and Order. And just because you fix a tire, doesn't mean you're knowledge or qualified to replace an engine block of fix a brake line.
But in Information Technology -- ever goober whose ever set up a home wireless router or wrote an HTML page back in '97 somehow think they can tell the network engineer how to spec out VLAN or a database administrator how to create an optimized query. Only in IT do our clients know so little but have so much power.