I completely concurre that identification is the main ingredient. As an example, when I was on the technical side with a major retailer and DVD was introduced, as a company some off our players would not play certain disks. Some major manufacturers also had this problem with their players. Was it the disk or was it the player? As you can imagine arguments ensued. I was given the unenviable task of finding the solution.
The dvd consortium issued two huge documents one was for the player manufacturers and one for the disk manufacturers. Call it the SDK of player and disk manufacture/authoring. Of course, as you mention, everything was written and made by humans. Like all documents of this type, some things were clear and some things were open to interpretation. A DVDs player is like a computer it has to have its own operating system written and it had to have the correct memory etc. The disk had to be authored so it too was reliant on a computer programme being written to correctly author the disk according to the SDK. So, was it the player? Was it the Disk? Was it the authoring tool? Who was suffering? Everyone! We were getting returns of players, the retailers selling the disks were getting returns and the big studios releasing blockbuster movies were not happy.
To cut a long story short, before a certain first for DVD blockbuster title was issued by one of the worlds biggest studios, so sales were expected to be huge I was already working with them to find the problem. Let's just say that by this time the legal eagles were starting to extend their tendrils so their was a lot of pressure. We brought together the manufacturers the studios and the authoring houses and because of one certain disk (a little like you finding the BGL) step one was accomplished.
People that say the words "bad code" simply show their lack of experience. Finding problems is about the detail and sometimes bringing all the different parties to the table. It's all about finding the hook and sometimes facilitating to solve the problem. In my example above, knowone had made an error everyone had done everything correctly, by the book, and the two books were huge. The issue was interpretation in this case. Step two followed quickly but their was also a step three which was solved and by getting everyone to talk and finding the hook, the problem had a resolution. I call it the Appolo 13 solution. The Luner module was made by one manufacturer, the command module by another. NASA issues the SDK and when that one in a million problem occurs, all the parties got together and solved it. Software is no different.