I managed to clear out a USB stick by deleting partitions. I expanded the first partition to the entire capacity of the USB (4G) and used gujin to 're-make' a bodhi linux iso with gujin bodhi_1.2.0.iso followed by cat bodhi_1.2.0.iso > /dev/sdb1 && sync. I was expecting the slightly-modified ISO to launch or show me its grub menu but I get a chksum error. I suppose the cat operation initialized it for me, and this was after I had gparted format the one partition as ext3. Any suggestions would be welcome.
You can either modify the ISO image by "gujin bodhi_1.2.0.iso" and then copy that device image on a USB, so that the MBR of the USB is the first sector of the modified bodhi_1.2.0.iso (first sector which will be loaded by the BIOS), or install Gujin on the USB (so that Gujin is the first sector of the USB) and copy an unmodified bodhi_1.2.0.iso inside a partition with "cat && sync".
You probably can also copy your Gujin-modified bodhi_1.2.0.iso inside a FAT/ext* partition of a USB if that USB has had an installation of Gujin in the MBR - but anyway you need to initialise the MBR of that USB with something executable, you did not so when doing: "gujin bodhi_1.2.0.iso followed by cat bodhi_1.2.0.iso > /dev/sdb1 && sync"
You can even use a standard MBR code on you current installed USB if you make the partition "bootable" (flag in the partition tool). The partition tool do not install a bootable MBR (just a blank one, not executable), you have to use another software for that, I think in debian it is mbr-udeb.
Do not forget to check that none of the partition of the USB are mounted before doing "dd" or "cat" to them, the initial filesystem superblock may be overwritten when automatic unmount is done - when you remove the USB disk.