OTOH, Greg, while I enjoy seeing a photo with smoke and steam billowing arouund a locomotive and appreciate the effort you photographers go to in order to get same, I really prefer to see a well-lit, clean shot of a locomotive doing its job under the hands of a skilled fireman who keeps the stack relatively clear, and in doing so helps the engineer operate it more efficiently. Back in the day the brass hats would be much happier with a clear stack as well. In addition, a good sharp photo without a lot of smoke allows one to see details a smoke-filled shot would not. Just my nickel's worth.
-- Ed