Bring your own cueball ?
On coin-op bar tables (newer ones), the standard size cueball is the regular size (2 1/4"), and has some iron in it, either a round core or particles throughout the balls surrounding area. The bar table magnetically sorts the cueball from the rest. The newest bar tables, (and still rarely seen), have an optic scanner to identify the cue ball marking and sort it that way. The old "rock" ball, now seen rarely on coin-op tables certainly should be replaced, no matter what the consequent other problems are created.
The problem with bringing out your own (pretty new) cue ball is that it is not worn down like the rest of the object balls, consequently it is both bigger and heavier. This creates a real problem to get used to the cue ball going too far (more mass) and, becauer its center is higher off the table, you can potentially jump the object ball off the table or off the rail onto the floor and foul.
Those that practice, (usually on a drop pocket bigger table), like the "measles" balls because they can see the spin and tell if the cueball was struck right.