Hi guys, I am a retired sbc tech who often ran in fiber optic cables all of which were glass. Due to crowding on racks they often got bent around all over the place but seldom had a failure which would
be indicated by errors in multiplexing equipment at end of transmission line. Finger prints and the associated oils from same could be a problem, so never touch either plastic or glass polished ends after the little caps are removed. The communication companies use nothing but glass fiber and seldom have a problem.
You don't want them too long where the lay on floor and get stepped on and the bends should be gentle with no kinks or knots and the same for the plastic ones. In the end the company quit using any liquid cleaner like alcohol based ones to clean suspected smudges from connectors but switched to a special wound tape that was swiped over polished end once, then advanced to a fresh patch of the tape, and maybe swiped one more time. They had a scope (handheld microscope) to examine the ends because the smudges and dirt cannot be seen with the naked eye. The light would also be measured in DB level with a test box.