I give my horns a monthly bath with detergent -- my old Recording had that smoker's smell which just wouldn't go away, but after a recent ultrasound clean it's fine. The technician who cleaned it said a fair bit of black stuff came out and he had to do some extra work to really clean it.
Perhaps I could have done a better job of cleaning the trumpet myself if I'd left it longer in the bath (rather than just 20 minutes or so). I had been using a "snake" but not much stuff came out with that -- perhaps it was really solidly bonded to the metal? Before the ultrasound clean I would have given it about 10 baths.