yeas I guess I should say, not an abrasive to a nes cart, it'll mess up clear coat and a CD case. I have NOT seen it change the texture of a nes cart though. You shouldn't be scrubbing with it like it's a sanding block, and it shouldn't take more than a few swipes over anything, if you're altering the texture of the nes cart, you're doing it wrong. It's not close to 1000 grit sandpaper though, not even close 2,000

This is dry, left is 1500 grit sand, right is the magic eraser, one pass. IF you do them wet, the left isn't as deep, and the right is undetectable from most angles. You have to do a few passes to do make damage.
My understanding of the foam, yes, there is some abrasion working, but it's not just sanding away the gunk, otherwise I'd be wet sanding my carts. The open cells break off like an eraser, with the gunk trapted inside.
Edit: Ok, so photobucket resized it so you can't see ANY mark on the right, it looks like a haze. Think about the damage done by rubbing two cases together, same thing.
Edit 2: Some drop box links, here's the photo above:
https://www.dropbox.com/s/1elmwdbe8b4nohf/2014-04-26%2023.04.12.jpgTwo pics of Chuck Rock II, cleaned about 15 mins ago with magic eraser + IPO, followed by armor all
https://www.dropbox.com/s/h7u6udcjtzaqkcg/2014-04-26%2023.16.51.jpghttps://www.dropbox.com/s/n5hgu42e4jm4sh1/2014-04-26%2023.17.10.jpgAnd I was going to see if you guys could spot which nes cart I cleaned this way, but it's not really fair. The one that I didn't use the magic eraser on looks like it has texture issues on the edges for some reason.
https://www.dropbox.com/s/p9dh1sswb7sqs0f/2014-04-26%2023.18.07.jpg^-- game should be relabeled as "Adventures of Slowdown and Flickerboy"