Before I left corporate America, I worked with a guy who was basically the definition of 'idiot savant' sans the actual diagnosis. He was ridiculously smart, but couldn't stay on task to save his life.

Like one time we landed a project with a major client. My team was running backend, his was running mobile integration. After a month of little to no visible activity, we approached him and he just said 'oh yea, i got sidetracked'... but he wasn't working on anything else. Just found some random shinny pebble that caught his attention and he bailed on everything else.

To make matters worse, his personal hygiene was nonexistent (I don't think he's showered since either), and he LOVED writing things in super-obscure languages that even the best we had hadn't ever heard of, with nonsensical (and often totally misleading) variable names and no inline comments. Trying to put someone new on something he'd touched was like asking an English professor to translate a 10K year old tablet dug up in the middle of the desert. Just didn't work.

But... the CEO flat out refused to get rid of him for years, until virtually every other employee simultaneously turned in our two weeks.