Why I would rather scrape gum off the bottoms of chairs than be a manager

Several years ago I had the responsibility of managing several librarians and one computer support person. Bob, one of the veteran librarians and a kind of self proclaimed computer maven resented Gary, the new and younger computer guy who obviously knew much more. Unlike Bob, Gary also liked to cut to the chase and just get things done without talking and thinking things to death. So he made himself useful around the place by fixing gliches and tweaking software--sometimes helping out and meeting with the folks in Bob's department without going through Bob (Bob had a point here). Gary also had a playful sense of humor and in an idle minute or two had decorated the small photo of the staff that he kept in his office by giving some extra "features" to each face. As I recall there was an arrow through my head, fangs on the boss, and something goulish on his own mug. Bob had horns. I didn't give this much thought until Bob showed up in my office with a grim look on his face. The conversation went something like this:

"I'd like to talk to you about Gary"
"OK. So what's the problem?"
"Did you see the staff photo in his office?"
"Yeah, I guess so."
"Did you see what he drew on my head?"
"I don't remember."
"Well, he's drew horns on me. I've got horns coming out of my head."
"Yeah," I said, trying not to laugh. "He put something on everybody. I think he put an arrow through my head."
"Well, on me, he put horns. He thinks I'm like the devil."
"I'm not sure I'd draw that conclusion."
"Yes, he does. That's why he picked horns for me. Why else would he do it?"
"Maybe he just chose the decorations at random."
"No, I'm sure that's not the case. He sees me pretty much as the enemy."
"Well, would you like me to say something to him?"
"Well that's up to you, but I don't see this situation getting any better."
"So you think there's a real problem here?"
"Well, yeah, don't you? I mean, look what he's done."
"OK, let me think about it."

A day later, I talk to Gary and tell him that Bob doesn't like his horns. Gary says he didn't mean to offend anybody; I say, I know that; Gary says he'll take the picture down and does so. End of story--I thought it had a point when I began but it obviously does not. Since I typed it all out, though, I'm posting it anyway.