Likewise, some organs naturally have dark colors.
However, appearance alone is not a reliable way to determine whether chicken is safe.
The most important factor is temperature and proper cooking.
For poultry, food-safety guidance commonly recommends cooking the thickest portion to an internal temperature of 165°F (74°C), measured with a food thermometer.
That is much more reliable than judging doneness by color alone.
The Bigger Danger May Be Raw Chicken
Ironically, one of the biggest food-safety problems associated with chicken isn't a particular “poisonous part.”
It's raw or undercooked poultry.
Chicken can become contaminated with pathogenic bacteria during processing and handling.
That's why you should:
Keep raw chicken refrigerated.
Wash your hands after handling raw poultry.
Use separate cutting boards when practical.
Clean surfaces that have contacted raw chicken.
Avoid eating chicken that remains undercooked.
Cook poultry thoroughly before serving.
One particularly important point: washing raw chicken isn't necessary and can actually spread bacteria around the kitchen through splashing water.
Cooking is what makes contaminated poultry substantially safer to eat.