Mark pointed out that only one chip type is vulnerable to BAD USB, id like to check if mine are, am using only Kingston flash drives here so can you tell me if they are, or if there exists a list somewhere i could check this? thank you.
You need to determine what flash controller your device has. Different devices may have different controllers even if they have the same manufacturer - it seems to only depend on what the factory had at the time.
One way is to disassemble the device and read the label on the controller chip
Another (non-invasive) way is to use software such as ChipGenius. This can be found via Google on a number of Russian sites. Make sure to check your copy for malware. "usbdev.ru" is one source of usb software/firmware programming files.
After you know the controller in use, you can search around to see if it is vulnerable or use / modify the manufacturer's firmware flashing tool to flash your own firmware onto it. If you succeed then the device is probably vulnerable. If afraid of "badusb" I would avoid micro-controller based memory controllers and stick to those which use single use chips.
Similar research was performed into flash memory in SD cards a while before "badusb" emerged and this CCC talk is quite interesting. It explains the reasoning behind using micro-controllers because of flash quality / economics. Much of the information applies to USB flash drives as well.
A quick Google search indicates that you can't really find that out without dismantling the device. Manufacturers can change controllers for an existing product.
The best defence is to not use a USB device that you have not purchased yourself.