The first thing the night cook checks is the colour of the smoke coming out of the stack (sample). Thick white smoke means the fire is starved of air and the meat will taste bitter.
What we want is a thin, pale blue haze you can barely see. It comes from a small, hot, clean fire: one split of seasoned oak at a time, with the firebox door cracked open.
It is also why our logs sit in the yard for a year before they burn. Wet wood smoulders; dry wood burns clean.