The problem with beading glass is that it's easy to rinse too fast.
we rinse from the top side to side bringing the brush down a little lower each time, but if you bring the brush down faster than the water runs away you will leave dirt behind.
Sometimes you can see rinsing water form tiny riverlets that flow down between the beads, of course the dirt in these beads will be left behind. I find it does a better job rinsing beading glass with the brush just on the glass, you are then breaking the surface tension of the beads as you go.
Sheeting glass is easy, we can rinse the whole pane from the top if we want to.