My general rule is that if its been working reliably and contributing to revenue generation its not bad code. We have code over 10 years old that looks bad by today's standards but since those are parts of the system that almost never need to be changed then there is absolutely no reason to try to make them better because they are already functional and battle tested. The concept of modern code is just a compulsion of developers to sprinkle their own beliefs of good coding standards over code that is application critical and should be resisted unless there is a good case behind it (e.g those components regularly cause instability or need to be extended)