> [... is this usb flash drive read-only? ...]

No tool will tell you whether the usb flash drive firmware
implements the read-only switch just by erroring all write requests
or by redirecting them to /dev/null (without bothering to set
the correct magic bits in the right magic code pages).

To know for sure, you have to write something and read it back.

Anyway, it is very academic because el6 and el7 desktop software will
unconditionally try to mount anything storage-like the moment you
plug it in.

Also good time to go for a coffee while "read error" and "resetting sata port"
and "cannot read super block" messages scroll by after you plug a sickly disk
into your test computer.

-- 
Konstantin Olchanski
Data Acquisition Systems: The Bytes Must Flow!
Email: olchansk-at-triumf-dot-ca
Snail mail: 4004 Wesbrook Mall, TRIUMF, Vancouver, B.C., V6T 2A3, Canada