I'm pretty sure erasers are supposed to make stuff lighter, NOT darker. Yet, no matter how often I "clean" mine off, it gets dirty again within two seconds and, yes, makes whatever I'm trying to erase darker. Maybe it has to do with the quality of the eraser, because mine's a relatively cheap one that came with my pencils (now the pencils were not cheap, but that's a whole 'nother story)
You know what I want? One of those kneaded eraser things. I've heard they're really useful, for small spaces and stuff.
Anyways, happy late Fourth, to all your Americans out there.