I've done a lot of both hardware and software, and I've seen a lot more bad software done by hardware engineers than I've seen bad hardware done by software engineers. The software guys usually know that they're out of their bailiwick when it comes to hardware design.
E.g. one of the worst in my experience was a 30,000 line shell script, few if any functions, used as part of our production flow. A simple refactoring could have cut it down at least 90%. Even worse, it was totally unsupported because the guy who wrote it was reassigned.