Just to add a datapoint, I've been making chip music for nearly 15 years and being able to accurately hear pulsewidth, waveform (assuming a simple, fundamental chiptune waveform like square, saw, triangle) is actually relatively common with a bit of experience.
When I got started I was awed by it in others I talked to on IRC, but it wasn't too long before I was familiar with it, too. It's also pretty easy for me—and I'd bet for nyanpasu64 as well—to identify the actual PSG or platform used and even to get a good idea of what sort of sequencing/programming is involved to get any particular sound I hear.
For me it's pretty specialized, though. I absolutely can't do that with traditional music production. I wouldn't be able to tell you too much about music I heard produced with modern tools.
