Wrong!
Different polishes have different levels of abrasion. Also, the contacts are not plated in gold. At least that's the general consensus. Now, I've had ISO (rubbing alcohol) be ineffective at cleaning many games. I've cleaned ALL my cartridge based games using metal polish and as long as I take care of them correctly, I shouldn't ever have to again. Also, polish is nowhere near the same level of abrasion as using fine grit sandpaper. Now, I've never used Brasso. I use a polish from the Nintendo Repair shop. It's very thin and it works great. What's disheartening is people making claims against a process without any proof. And anyone that would claim that ANY grit of sandpaper might not be as damaging as polish, well I would say their OPINION is very suspect as they obviously don't know much. If you're going to make these claims, I suggest you post proof that Brasso is actually causing the failure of a game. Also, as I said, not all polishes are the same. Some polishes are meant for certain metals. In Brasso's case, brass. Also, pencil erasers? I bet you think using WD-40 is a great idea too?
All of my games work and they've all been cleaned using polish. In fact, my NES game all work first time, every time since cleaning them. When before they had a lot of problems working. Also, the NES is untouched internally since the day it was opened for Toys R' Us. It hasn't even been cleaned. Here's some picture evidence of a copy of Megaman 2 which had some heavy corrosion and it required a lot of pressure, and two passes to get it off. From looking at them, the so called "gold" is still there.