I've polished to a practically mirror shine with progressively finer and finer grit sandpaper. Took an eternity. Worked for the purple I was using, but it might not work for all colours.
I've also tried heating PETG with a butane lighter out of pure frustration. It does work, but the line between restoring the surface finish and deforming the print is very thin.
Wow, after reading your story, my ragequit is peanuts in comparison. I almost don't feel like posting it!
Normally I'm a lot more humble than this, but you're all strangers on the Internet, so you'll just have to take my word for it, but... I had performed extremely well at my software development job. "Exceeds expectations" kind of performance review. I had led the architecture of several large efforts, and consistently delivered features.
Promotion time comes around, and I get a 3% raise. Eh, whatever. At least it meets inflation.
I find out a bit later that one of my coworkers (quite talented in her own right, don't get me wrong) got a title increase and a much more meaningful salary bump.
So I talk to my manager about why she was promoted and I wasn't. We both had similar performance reviews, had led similar projects, and so on. I was prepared to accept it if there was a good reason. There wasn't. There was only budget room for one promotion, and she had been hired at a more senior position than me, though I had been promoted to match soon after I started. That's it. No logical reason other than seniority.
I was butthurt, and started looking for a new job right away. Ended up snagging a great gig in a few weeks.
I keep in touch with my old co-workers quite regularly, and I guess some activist investor forced through policy changes and gutted the satellite office I worked at. I guess I dodged a bullet there.
Peel them first, we aren't trying to get murdered here.