I have the same issue on a late 2013 Macbook Pro 15inch. I booted into Recovery mode, and selected to install new Mavericks, and chose my USB drive as the target.
The installer correctly downloads to the USB, and the bootable USB works fine on my old 2010 macbook pro. However, the USB drive does not show when i boot with option pressed. It is as if the Macbook just dont permit booting from USB - eventhough the drive was created on the very same mac.
Anyone have a clue as to how to boot from USB?