There is absolutely nothing scientific about anything you guys are talking about. Actually, the 1-100 scale is probably more universal as it's just 'how loud, on the scale from quietest to loudest, do you keep your speakers', as opposed to dB-SPL ratings which no one on the Escapist has the equipment to measure in their home.
OT EDIT: I crank pretty much everything, but I keep things at a reasonable volume if other people are around, mostly because I don't want other people to hear something horrible come out of my speakers, like if I'm listening to Walking the Room.