Who do I like to operate on?

During their break from work, four surgeons were sitting around discussing who they like to operate on.
The first surgeon said, "I like operating on librarians. When you open them up everything is in alphabetical order".
The second surgeon said, "I like operating on accountants. When you open them up everything is in numerical order".
The third surgeon said, "I like operating on electricians. When you open them up everything is color coded.
The fourth surgeon said, "I like operating on lawyers."
The other three surgeons looked at each other in disbelief. One of them asked why.
The fourth surgeon replied, "Because they are heartless, gutless, spineless, and their butt and head are interchangeable".