I recall about 6 months ago an article by someone like Consumer's Reports that talked about the Magic Eraser. The magic in it is a micro-abrasive compound that they bonded to the sponge like carrier. They said it does work. But they also said that the bonding agent used to keep it all together was real bad stuff.
Sorry I can't find the article to get the details more accurately, but after discovering how well it worked, then hearing this news, I trashed the rest of them. Sort of like the Teflon deal except the bad stuff got revealed within months of the marketing launch. Despite this, I think they're selling tons of it.

I will certainly never put it in the pool.