I don't treat my helmets with nearly the care I do my iPhone
Just as a note to everyone: If you drop your helmet, you should throw it away. You can't tell if the foam has been cracked, which reduces its protection.
This is a pretty common misconception. Info from Snell Foundation: http://www.smf.org/helmetfaq#aDroppedHelmet
Most manufacturers also offer a free inspection service where you can ship them your helmet and they'll check on the internals/foam.