You start basting with barbecue sauce immediately
THE RESULT: Sugary sauces scorch.
THE FIX: Sugar burns very quickly over high heat. When grilling with sweet, sugar-based sauces (several kinds of barbecue sauces fall into this category), always add them at the end of the cooking time (within the last 15 to 20 minutes), or use them when cooking over indirect heat. When using leftover marinade, don’t baste during the last 5 minutes of grill time, or you might not allow enough time for the heat to kill any bacteria that may be present.