The first sign of poor cable management is when you can't tell where one cable begins or ends. If you have to play detective just to find the power cable or trace a wire all the way from your device ...
I'll be honest with you, I've never really bothered with "real" cable management when building any of my PCs over the years. I started to care a little more when computer cases got side windows, but ...
Clean runs everywhere, at minimal expense ...