Been playing since 60's and never saw it done since streaming days now. Naturally I myself would wipe a cue ball now and then. This a scrapping method?
Yeah. Off of the cue ball and right back on the rail so it can get on the cue ball again. Doesn't make any sense at all, but nowadays not a lot does make sense.
Someone should do a controlled experiment to test whether most of the chalk that is transfered to the cueball during play is from tip to cueball contact or the cueball contacting the headrail and picking up remnant chalk from it.
It harkens back to ancient times. It's supposed to rub the evil spirits from off the surface of the ball.
In modern times it's suppose to wipe the crud off the surface of the ball which is pretty much the same thing.