The best appraoch to hide the joints is start with a good mason and have the joints cut flush, so the can be hidden by a heavy coat of some sort of "masonry" paint, or better, use two coats of Thoroseal and then apply any king of coating you wish because it is not a paint, but a cement based coating that actually becomes part of the wall (not like DryLok, that is a ""paint").
If you already have the wall, just go with a stucco finish.
Dick