I've been playing music games for about 15 years now. I started on a crappy DDR mat at home, even now I still have a Cobalt Flux I regularly use. I also played stepmania, Taiko no tatsujin, GH, and more recently a lot of Soundboxing. I think all this experience helps me figuring out what makes a good song or not, though I agree it's also very subjective. Hopefully my input will help you dissociate the gems from the turds.