Thanks for testing, Werner.

I verified my failed USB format (done via Knoppix EN CD) before retesting.
Code:
gparted gave FAT32 with boot & lba bits set
fdisk gave "Id c" "W95 FAT32 (LBA)"
cfdisk gave vfat with boot & NC flags set
cfdisk man page says:
The flags can be Boot, which designates a bootable partition or NC, which stands for "Not Compatible with DOS or OS/2". DOS, OS/2 and possibly other operating systems require the first sector of the first partition on the disk and all logical partitions to begin on the second head.
OK, So I booted my Knoppix CD, ran the flash installer again and got another unbootable USB.

I checked the partition specifications with Gparted, fdisk, and cfdisk and got exactly the same partition information as the previous test.

I then used Pendrive's Universal USB Installer under Windows Vista to write the Knoppix .iso to USB. I got the normal 704 MB FAT32/6.6 GB reiser fs partitioning, and the USB was bootable.

What was most interesting was that the partition info under Gparted, fdisk, and cfdisk were exactly the same as the previous 2 tests.

Therefore, the difference between bootable and non-bootable boot records and/or partition 1 information is not something I can see with any of the three tools.

FWIW, the flash device is a Crucial 8 GB.