The art of runby smoke

It would be interesting to hear some stories by the folks who have run steam for runbys. How to do it, and how maybe not to do it, etc. I learned a bit about firing oil burning engines a looooong time ago, but never fired coal, and never did runbys. As a photographer I have seen all kinds of runby plumes, from great to terrible. The art of the runby smoke plume is often to make an engine look like it is working when it is not. Worst case downhill. Smoke in and of itself is not enough. You need the lift associated with a hard exhaust, and just enough smoke to simulate the efforts of a fireman to make as much steam as quickly as the boiler is willing without wasting (too much) fuel. Then there are the problems associated with overfiring....a bad fire, sand in the firebox, even firebox damage. I suspect some posters here might have some good stories.

JBWX