it is easy to burn a chicken on a grill. I've done it often during a barbeque.
In the process I became a master-taster and have now found the perfect grilled chicken!
In Lisbon, Portugal in the street Restauradores it gives the restaurant "El Rey del Frangos" or tranlated the King of Chickens and they roast chickens over a big charcoal fire for about 30 minutes. The chicken is marinated, salted with large sea-salt chunks and covered with a special piri-piri sauce (means HOT)
The restaurant is always full, the cook must roast hundreds of chickens a day, and afterwards you pay for chicken+fries+salad+wine+bread+cheese+water+coffee about €15 or less than USD 20
You just have to go to Lisbon for it!