The phrase "look sour" can be replaced by various synonyms depending on the context and the intensity of the emotion. Some milder expressions include "frown," "grimace," "scowl," or "pout." These words indicate a sense of displeasure or dissatisfaction. On the other hand, some stronger synonyms for "look sour" could be "glower," "scowl fiercely," "shoot daggers," or "curl one's lip." These words convey a sense of anger or contempt. Whatever the synonym used, it's essential to match the intended emotion accurately, ensuring effective communication with the audience.