I came upon a guy one day cyling an old 1980s all-steel racer lookalike. Some of the cables clearly weren't connected to anything, the chain made a constant loud squealing, the steel rims were visibly wobbling, and, best of all, the left crank connected with the chainstay every third or fourth rotation, clearly loose on the bottom bracket axle. Whenever he didn't remember to push it away from the chainstay with his foot: crash!
The thing is, he was doing a cracking pace. In the gutter, but maintaining a good 20 mph plus. We chatted for a while, leaving me out of breath. I left him thinking, if he was on a decent bike, or even one with a bit less friction going on, he'd really shift.