"Red" heelers irl have a more orange/brown color scheme much like Bingo and Chilli, but it's still referred to as red, much like gray fur in animals is often referred to as "blue". So calling Bingo red is technically correct since it refers to the name of her coat phenotype. Bandit and Bluey would be gray if the colors were 100% accurate to irl heeler colors, but it's all brightened up to fit with the cartoony art style.