The first net-negative programmer I ever met was on a consulting project that had been set up in a hurry so devs were hired after a brief phone screen. Until then I had heard of NNP’s but wasn’t sure they existed. Ron changed my mind. We started giving him simple jobs, then when he failed we gave him simpler jobs, then when he failed again we just made up a few make-work tasks having nothing to do with the system we were working on. He’d try, but his efforts would always break things so we ended up writing a short script called “un-ron” that would check the commit history for his commits and revert them.