Tasting dirty, like rolling around in a fire, is ash on the meat. If the thighs were skin on, you were getting a lot of fat dripping on a hot fire. Throwing fat on a fire is not a lot different than throwing fuel on a fire. You'll get flare-ups than can carry the ash off the coals into the heat plume. That ash will stick to the meat. The flare-ups can burn the meat, too.
Just an idea to consider.
Just an idea to consider.
