Grease on the ball?

SDcampowneroperator wrote:
Never have. Grease on the ball is an as you wish. Come on now think about it, that. ball and hitch does not move more than you turn. Wheres the wear?

The wear is on the ball where it can get galled and scratched badly. In fact there have been many cases of whole chunks of the ball being torn out by the coupler. There is also considerable wear on the coupler itself.
In addition, the friction between the coupler and ball has frequently been known to turn the ball and loosen it up.

Grease it if you want, do not be concerned with wear.

Very bad advice!

Does the owners manual of your hiitch recommend grease? I bet not.

You lose that bet! A quote or two from the Reese Round Bar Installation instructions.
"Apply a heavy fibrous grease on the round end of each spring bar and push end up into head socket until you hear a click."
Also,
"MAINTENANCE
Keep the round ends of the spring bars and the sockets in the head assembly free from dirt and well lubricated. Excessive wear in this
area may indicate an overload or inadequate lubrication."
Also,
"AT THE BEGINNING OF EVERY TOWING DAY
Coat the round ends of the spring bars with a fibrous grease. Clean ball and coupler socket and coat ball lightly with grease."

Equalizer bars get more movement and wear than the ball, but still no reason to grease them. They will never wear out, and might also through friction give a bit more sway control.

Evidently you have never looked closly at a spring bar that has been used for some time without grease. Same goes for the sockets that they insert into. Both the bars and sockets will wear out into an oval shape and after a while will recuce the amount of WD that the bar can provide using the same chain links. If enough time has passed, the whole hitch head will probably have to be replaced.