For me, it's knowing it's KFC, an establishment whose food always tries my digestion. In addition, two hunks of deep-fried breaded (or even grilled) chicken, aside from being unpleasant to handle with one's bare hands, not only seem like overkill but also throw off the chicken-bacon/cheese proportion.
A lovely homemade chicken cordon bleu,* on the other hand, is a thing of beauty.
*Or one prepared in a decent restaurant.