Yep. It's something people rarely think about. I've only seen it in a few cases with mainstream comics; The Flash seems to use it almost entirely as comic relief. More realistically, given the widespread use of synthetics, if he grabbed a random person and ran with them, the friction would usually melt their clothes. Not so funny. A few times I've made torches from socks that turned out not to be all cotton as claimed -- the stuff is like napalm. 0_o